Bootstrap4官方文档 | v4核心 -- 组件(二)

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Bootstrap是一个简洁、直观、强悍的前端开发框架，让web开发更迅速、简单。是全球最流行的前端框架，用于构建响应式、移动设备优先的 WEB 站点。

入门Bootstrap4

组件

表单

表单控件样式，布局选项和用于创建各种表单的自定义组件的示例和使用指南

<form>
  <div class="form-group">
    <label for="exampleInputEmail1">电子邮件地址</label>
    <input type="email" class="form-control" id="exampleInputEmail1" aria-describedby="emailHelp">
    <small id="emailHelp" class="form-text text-muted">我们不会向任何人透露您的邮件地址</small>
  </div>
  <div class="form-group">
    <label for="exampleInputPassword1">密码</label>
    <input type="password" class="form-control" id="exampleInputPassword1">
  </div>
  <div class="form-group form-check">
    <input type="checkbox" class="form-check-input" id="exampleCheck1">
    <label class="form-check-label" for="exampleCheck1">检查</label>
  </div>
  <button type="submit" class="btn btn-primary">提交</button>
</form>

表单控件

文本形式的控件（如<input>，<select>和<textarea>）使用.form-control该类设置样式。其中包括用于一般外观，焦点状态，大小调整等的样式。

确保探索我们的自定义表单以进一步样式化<select>。

<form>
  <div class="form-group">
    <label for="exampleFormControlInput1">Email address</label>
    <input type="email" class="form-control" id="exampleFormControlInput1" placeholder="[email protected]">
  </div>
  <div class="form-group">
    <label for="exampleFormControlSelect1">Example select</label>
    <select class="form-control" id="exampleFormControlSelect1">
      <option>1</option>
      <option>2</option>
      <option>3</option>
      <option>4</option>
      <option>5</option>
    </select>
  </div>
  <div class="form-group">
    <label for="exampleFormControlSelect2">Example multiple select</label>
    <select multiple class="form-control" id="exampleFormControlSelect2">
      <option>1</option>
      <option>2</option>
      <option>3</option>
      <option>4</option>
      <option>5</option>
    </select>
  </div>
  <div class="form-group">
    <label for="exampleFormControlTextarea1">Example textarea</label>
    <textarea class="form-control" id="exampleFormControlTextarea1" rows="3"></textarea>
  </div>
</form>

对于文件输入，将替换.form-control为.form-control-file。

<form>
  <div class="form-group">
    <label for="exampleFormControlFile1">示例文件输入</label>
    <input type="file" class="form-control-file" id="exampleFormControlFile1">
  </div>
</form>

大小

使用类.form-control-lg和设置高度.form-control-sm。

<input class="form-control form-control-lg" type="text" placeholder=".form-control-lg">
<input class="form-control" type="text" placeholder="Default input">
<input class="form-control form-control-sm" type="text" placeholder=".form-control-sm">

<select class="form-control form-control-lg">
  <option>Large select</option>
</select>
<select class="form-control">
  <option>Default select</option>
</select>
<select class="form-control form-control-sm">
  <option>Small select</option>
</select>

只读

readonly在输入上添加布尔属性，以防止修改输入的值。只读输入看起来较浅（就像禁用的输入一样），但保留了标准光标。

<input class="form-control" type="text" placeholder="只读输入在这里..." readonly>

只读纯文本

如果希望<input readonly>表单中的元素以纯文本样式设置，请使用.form-control-plaintext该类删除默认的表单字段样式，并保留正确的边距和填充。

<form>
  <div class="form-group row">
    <label for="staticEmail" class="col-sm-2 col-form-label">电子邮件</label>
    <div class="col-sm-10">
      <input type="text" readonly class="form-control-plaintext" id="staticEmail" value="[email protected]">
    </div>
  </div>
  <div class="form-group row">
    <label for="inputPassword" class="col-sm-2 col-form-label">密码</label>
    <div class="col-sm-10">
      <input type="password" class="form-control" id="inputPassword">
    </div>
  </div>
</form>

<form class="form-inline">
  <div class="form-group mb-2">
    <label for="staticEmail2" class="sr-only">Email</label>
    <input type="text" readonly class="form-control-plaintext" id="staticEmail2" value="[email protected]">
  </div>
  <div class="form-group mx-sm-3 mb-2">
    <label for="inputPassword2" class="sr-only">密码</label>
    <input type="password" class="form-control" id="inputPassword2" placeholder="Password">
  </div>
  <button type="submit" class="btn btn-primary mb-2">确认身份</button>
</form>

范围输入

使用设置水平滚动范围输入.form-control-range。

<form>
  <div class="form-group">
    <label for="formControlRange">范围输入示例</label>
    <input type="range" class="form-control-range" id="formControlRange">
  </div>
</form>

复选框和单选框

默认复选框和收音机时的帮助下提高.form-check，单一类改善他们的HTML元素的布局和行为都输入类型。复选框用于选择列表中的一个或多个选项，而单选框则用于从多个选项中选择一个选项。

支持禁用的复选框和收音机。该disabled属性将应用较浅的颜色，以帮助指示输入的状态。

复选框和单选按钮支持基于HTML的表单验证，并提供简洁，可访问的标签。因此，我们的<input>和<label>如相对于一个同级元素<input>内的<label>。这有点冗长，因为您必须指定id和for属性以关联<input>和<label>。

<div class="form-check">
  <input class="form-check-input" type="checkbox" value="" id="defaultCheck1">
  <label class="form-check-label" for="defaultCheck1">
    Default checkbox
  </label>
</div>
<div class="form-check">
  <input class="form-check-input" type="checkbox" value="" id="defaultCheck2" disabled>
  <label class="form-check-label" for="defaultCheck2">
    Disabled checkbox
  </label>
</div>

<div class="form-check">
  <input class="form-check-input" type="radio" name="exampleRadios" id="exampleRadios1" value="option1" checked>
  <label class="form-check-label" for="exampleRadios1">
    Default radio
  </label>
</div>
<div class="form-check">
  <input class="form-check-input" type="radio" name="exampleRadios" id="exampleRadios2" value="option2">
  <label class="form-check-label" for="exampleRadios2">
    Second default radio
  </label>
</div>
<div class="form-check">
  <input class="form-check-input" type="radio" name="exampleRadios" id="exampleRadios3" value="option3" disabled>
  <label class="form-check-label" for="exampleRadios3">
    Disabled radio
  </label>
</div>

行内

通过将复选框或单选框添加.form-check-inline到同一水平行来对它们进行分组.form-check。

<div class="form-check form-check-inline">
  <input class="form-check-input" type="checkbox" id="inlineCheckbox1" value="option1">
  <label class="form-check-label" for="inlineCheckbox1">1</label>
</div>
<div class="form-check form-check-inline">
  <input class="form-check-input" type="checkbox" id="inlineCheckbox2" value="option2">
  <label class="form-check-label" for="inlineCheckbox2">2</label>
</div>
<div class="form-check form-check-inline">
  <input class="form-check-input" type="checkbox" id="inlineCheckbox3" value="option3" disabled>
  <label class="form-check-label" for="inlineCheckbox3">3 (disabled)</label>
</div>

<div class="form-check form-check-inline">
  <input class="form-check-input" type="radio" name="inlineRadioOptions" id="inlineRadio1" value="option1">
  <label class="form-check-label" for="inlineRadio1">1</label>
</div>
<div class="form-check form-check-inline">
  <input class="form-check-input" type="radio" name="inlineRadioOptions" id="inlineRadio2" value="option2">
  <label class="form-check-label" for="inlineRadio2">2</label>
</div>
<div class="form-check form-check-inline">
  <input class="form-check-input" type="radio" name="inlineRadioOptions" id="inlineRadio3" value="option3" disabled>
  <label class="form-check-label" for="inlineRadio3">3 (disabled)</label>
</div>

没有标签

添加.position-static到.form-check其中没有任何标签文本的输入中。请记住，仍要为辅助技术提供某种形式的可访问名称（例如，使用aria-label）。

<div class="form-check">
  <input class="form-check-input position-static" type="checkbox" id="blankCheckbox" value="option1" aria-label="...">
</div>
<div class="form-check">
  <input class="form-check-input position-static" type="radio" name="blankRadio" id="blankRadio1" value="option1" aria-label="...">
</div>

表单布局

由于引导应用display: block和width: 100%几乎所有的表单控件，表格会默认堆栈垂直。可以使用其他类来根据表单更改此布局。

表格组

该.form-group是一些结构添加到形式最简单的方法。它提供了一个灵活的类，它鼓励标签，控件，可选的帮助文本和表单验证消息的正确分组。默认情况下，它仅适用margin-bottom，但会.form-inline根据需要选择其他样式。与<fieldset>，<div>或几乎其他任何元素一起使用。

<form>
  <div class="form-group">
    <label for="formGroupExampleInput">标签示例</label>
    <input type="text" class="form-control" id="formGroupExampleInput" placeholder="Example input placeholder">
  </div>
  <div class="form-group">
    <label for="formGroupExampleInput2">另一个标签示例</label>
    <input type="text" class="form-control" id="formGroupExampleInput2" placeholder="Another input placeholder">
  </div>
</form>

表格网格

可以使用我们的网格类构建更复杂的表单。将它们用于需要多列，可变宽度和其他对齐选项的表单布局。

<form>
  <div class="row">
    <div class="col">
      <input type="text" class="form-control" placeholder="First name">
    </div>
    <div class="col">
      <input type="text" class="form-control" placeholder="Last name">
    </div>
  </div>
</form>

表格行

您也可以互换.row的.form-row，覆盖缺省列排水沟更严格和更紧凑的布局，我们的标准网格行的变化。

<form>
  <div class="form-row">
    <div class="col">
      <input type="text" class="form-control" placeholder="First name">
    </div>
    <div class="col">
      <input type="text" class="form-control" placeholder="Last name">
    </div>
  </div>
</form>

也可以使用网格系统创建更复杂的布局。

<form>
  <div class="form-row">
    <div class="form-group col-md-6">
      <label for="inputEmail4">邮箱</label>
      <input type="email" class="form-control" id="inputEmail4">
    </div>
    <div class="form-group col-md-6">
      <label for="inputPassword4">密码</label>
      <input type="password" class="form-control" id="inputPassword4">
    </div>
  </div>
  <div class="form-group">
    <label for="inputAddress">地址</label>
    <input type="text" class="form-control" id="inputAddress" placeholder="1234 Main St">
  </div>
  <div class="form-group">
    <label for="inputAddress2">地址2</label>
    <input type="text" class="form-control" id="inputAddress2" placeholder="Apartment, studio, or floor">
  </div>
  <div class="form-row">
    <div class="form-group col-md-6">
      <label for="inputCity">城市</label>
      <input type="text" class="form-control" id="inputCity">
    </div>
    <div class="form-group col-md-4">
      <label for="inputState">区</label>
      <select id="inputState" class="form-control">
        <option selected>选择</option>
        <option>...</option>
      </select>
    </div>
    <div class="form-group col-md-2">
      <label for="inputZip">Zip</label>
      <input type="text" class="form-control" id="inputZip">
    </div>
  </div>
  <div class="form-group">
    <div class="form-check">
      <input class="form-check-input" type="checkbox" id="gridCheck">
      <label class="form-check-label" for="gridCheck">
        选择我
      </label>
    </div>
  </div>
  <button type="submit" class="btn btn-primary">登录</button>
</form>

水平形式

通过将.row类添加到表单组并使用这些.col-*-*类指定标签和控件的宽度，可以使用网格创建水平表单。请务必同时添加，.col-form-label以<label>使它们与相关的表单控件垂直居中。

有时，您可能需要使用边距或填充实用程序来创建所需的完美对齐方式。例如，我们删除padding-top了堆叠式无线电输入标签上的，以更好地对齐文本基线。

<form>
  <div class="form-group row">
    <label for="inputEmail3" class="col-sm-2 col-form-label">Email</label>
    <div class="col-sm-10">
      <input type="email" class="form-control" id="inputEmail3">
    </div>
  </div>
  <div class="form-group row">
    <label for="inputPassword3" class="col-sm-2 col-form-label">Password</label>
    <div class="col-sm-10">
      <input type="password" class="form-control" id="inputPassword3">
    </div>
  </div>
  <fieldset class="form-group">
    <div class="row">
      <legend class="col-form-label col-sm-2 pt-0">Radios</legend>
      <div class="col-sm-10">
        <div class="form-check">
          <input class="form-check-input" type="radio" name="gridRadios" id="gridRadios1" value="option1" checked>
          <label class="form-check-label" for="gridRadios1">
            First radio
          </label>
        </div>
        <div class="form-check">
          <input class="form-check-input" type="radio" name="gridRadios" id="gridRadios2" value="option2">
          <label class="form-check-label" for="gridRadios2">
            Second radio
          </label>
        </div>
        <div class="form-check disabled">
          <input class="form-check-input" type="radio" name="gridRadios" id="gridRadios3" value="option3" disabled>
          <label class="form-check-label" for="gridRadios3">
            Third disabled radio
          </label>
        </div>
      </div>
    </div>
  </fieldset>
  <div class="form-group row">
    <div class="col-sm-2">Checkbox</div>
    <div class="col-sm-10">
      <div class="form-check">
        <input class="form-check-input" type="checkbox" id="gridCheck1">
        <label class="form-check-label" for="gridCheck1">
          Example checkbox
        </label>
      </div>
    </div>
  </div>
  <div class="form-group row">
    <div class="col-sm-10">
      <button type="submit" class="btn btn-primary">Sign in</button>
    </div>
  </div>
</form>

水平表格标签大小

一定要使用.col-form-label-sm或.col-form-label-lg您的<label>或<legend>到正确遵循的大小.form-control-lg和.form-control-sm。

<form>
  <div class="form-group row">
    <label for="colFormLabelSm" class="col-sm-2 col-form-label col-form-label-sm">Email</label>
    <div class="col-sm-10">
      <input type="email" class="form-control form-control-sm" id="colFormLabelSm" placeholder="col-form-label-sm">
    </div>
  </div>
  <div class="form-group row">
    <label for="colFormLabel" class="col-sm-2 col-form-label">Email</label>
    <div class="col-sm-10">
      <input type="email" class="form-control" id="colFormLabel" placeholder="col-form-label">
    </div>
  </div>
  <div class="form-group row">
    <label for="colFormLabelLg" class="col-sm-2 col-form-label col-form-label-lg">Email</label>
    <div class="col-sm-10">
      <input type="email" class="form-control form-control-lg" id="colFormLabelLg" placeholder="col-form-label-lg">
    </div>
  </div>
</form>

列大小

如前面的示例所示，我们的网格系统允许您.col在.row或内放置任意数量的.form-row。他们将在它们之间平均分配可用宽度。您还可以选择列的子集来占用更多或更少的空间，而其余的.cols用其他特定的列类（例如）平均分配其余部分.col-7。

<form>
  <div class="form-row">
    <div class="col-7">
      <input type="text" class="form-control" placeholder="City">
    </div>
    <div class="col">
      <input type="text" class="form-control" placeholder="State">
    </div>
    <div class="col">
      <input type="text" class="form-control" placeholder="Zip">
    </div>
  </div>
</form>

自动调整大小

下面的示例使用flexbox实用工具将内容垂直居中并更改 .col为.col-auto以便您的列仅占用所需的空间。换句话说，该列将根据内容自行调整大小。

<form>
  <div class="form-row align-items-center">
    <div class="col-auto">
      <label class="sr-only" for="inlineFormInput">Name</label>
      <input type="text" class="form-control mb-2" id="inlineFormInput" placeholder="Jane Doe">
    </div>
    <div class="col-auto">
      <label class="sr-only" for="inlineFormInputGroup">Username</label>
      <div class="input-group mb-2">
        <div class="input-group-prepend">
          <div class="input-group-text">@</div>
        </div>
        <input type="text" class="form-control" id="inlineFormInputGroup" placeholder="Username">
      </div>
    </div>
    <div class="col-auto">
      <div class="form-check mb-2">
        <input class="form-check-input" type="checkbox" id="autoSizingCheck">
        <label class="form-check-label" for="autoSizingCheck">
          Remember me
        </label>
      </div>
    </div>
    <div class="col-auto">
      <button type="submit" class="btn btn-primary mb-2">Submit</button>
    </div>
  </div>
</form>

可以再次将其与特定于大小的列类重新混合。

<form>
  <div class="form-row align-items-center">
    <div class="col-sm-3 my-1">
      <label class="sr-only" for="inlineFormInputName">Name</label>
      <input type="text" class="form-control" id="inlineFormInputName" placeholder="Jane Doe">
    </div>
    <div class="col-sm-3 my-1">
      <label class="sr-only" for="inlineFormInputGroupUsername">Username</label>
      <div class="input-group">
        <div class="input-group-prepend">
          <div class="input-group-text">@</div>
        </div>
        <input type="text" class="form-control" id="inlineFormInputGroupUsername" placeholder="Username">
      </div>
    </div>
    <div class="col-auto my-1">
      <div class="form-check">
        <input class="form-check-input" type="checkbox" id="autoSizingCheck2">
        <label class="form-check-label" for="autoSizingCheck2">
          Remember me
        </label>
      </div>
    </div>
    <div class="col-auto my-1">
      <button type="submit" class="btn btn-primary">Submit</button>
    </div>
  </div>
</form>

还支持自定义表单控件。

<form>
  <div class="form-row align-items-center">
    <div class="col-auto my-1">
      <label class="mr-sm-2 sr-only" for="inlineFormCustomSelect">Preference</label>
      <select class="custom-select mr-sm-2" id="inlineFormCustomSelect">
        <option selected>Choose...</option>
        <option value="1">One</option>
        <option value="2">Two</option>
        <option value="3">Three</option>
      </select>
    </div>
    <div class="col-auto my-1">
      <div class="custom-control custom-checkbox mr-sm-2">
        <input type="checkbox" class="custom-control-input" id="customControlAutosizing">
        <label class="custom-control-label" for="customControlAutosizing">Remember my preference</label>
      </div>
    </div>
    <div class="col-auto my-1">
      <button type="submit" class="btn btn-primary">Submit</button>
    </div>
  </div>
</form>

内联表格

使用.form-inline该类可在单个水平行上显示一系列标签，表单控件和按钮。内联表单中的表单控件与其默认状态略有不同。

• 控件是display: flex，可以折叠任何HTML空格，并允许您提供带有空格和flexbox实用程序的对齐控件。
• 控件和输入组接收width: auto以覆盖Bootstrap默认值width: 100%。
• 控件仅在宽度至少为576像素的视口中内嵌显示，以解决移动设备上的视口狭窄的问题。

您可能需要使用间距实用程序手动解决单个表单控件的宽度和对齐问题（如下所示）。最后，<label>即使您需要使用来向非屏幕阅读者隐藏它，也请确保始终在每个表单控件中都包含一个.sr-only。

<form class="form-inline">
  <label class="sr-only" for="inlineFormInputName2">Name</label>
  <input type="text" class="form-control mb-2 mr-sm-2" id="inlineFormInputName2" placeholder="Jane Doe">

  <label class="sr-only" for="inlineFormInputGroupUsername2">Username</label>
  <div class="input-group mb-2 mr-sm-2">
    <div class="input-group-prepend">
      <div class="input-group-text">@</div>
    </div>
    <input type="text" class="form-control" id="inlineFormInputGroupUsername2" placeholder="Username">
  </div>

  <div class="form-check mb-2 mr-sm-2">
    <input class="form-check-input" type="checkbox" id="inlineFormCheck">
    <label class="form-check-label" for="inlineFormCheck">
      Remember me
    </label>
  </div>

  <button type="submit" class="btn btn-primary mb-2">Submit</button>
</form>

帮助文字

可以使用.form-text（以前在v3中称为.help-block）创建表单中的块级帮助文本。可以使用任何内联HTML元素和实用程序类（如）灵活地实现内联帮助文本.text-muted。

<label for="inputPassword5">密码</label>
<input type="password" id="inputPassword5" class="form-control" aria-describedby="passwordHelpBlock">
<small id="passwordHelpBlock" class="form-text text-muted">
  您的密码长度必须为8-20个字符，包含字母和数字，并且不得包含空格，特殊字符或表情符号。
</small>

嵌入式文本可以使用任何典型的内嵌HTML元素（可以是一个 <small>，<span>或别的东西），有什么比一个实用工具类的更多。

<form class="form-inline">
  <div class="form-group">
    <label for="inputPassword6">密码</label>
    <input type="password" id="inputPassword6" class="form-control mx-sm-3" aria-describedby="passwordHelpInline">
    <small id="passwordHelpInline" class="text-muted">
     必须是8-20个字符长。
    </small>
  </div>
</form>

禁用表格

disabled在输入上添加布尔属性，以防止用户交互并使它看起来更浅。

<input class="form-control" id="disabledInput" type="text" placeholder="Disabled input here..." disabled>

将disabled属性添加到中<fieldset>以禁用其中的所有控件。

<form>
  <fieldset disabled>
    <div class="form-group">
      <label for="disabledTextInput">禁止输入</label>
      <input type="text" id="disabledTextInput" class="form-control" placeholder="Disabled input">
    </div>
    <div class="form-group">
      <label for="disabledSelect">禁止选择菜单</label>
      <select id="disabledSelect" class="form-control">
        <option>禁止选择</option>
      </select>
    </div>
    <div class="form-group">
      <div class="form-check">
        <input class="form-check-input" type="checkbox" id="disabledFieldsetCheck" disabled>
        <label class="form-check-label" for="disabledFieldsetCheck">
          无法选中
        </label>
      </div>
    </div>
    <button type="submit" class="btn btn-primary">提交</button>
  </fieldset>
</form>

验证方式

自定义样式

对于自定义的Bootstrap表单验证消息，您需要将novalidateboolean属性添加到<form>。这将禁用浏览器的默认反馈工具提示，但仍提供对JavaScript中的表单验证API的访问。尝试提交以下表格；我们的JavaScript会拦截“提交”按钮，并将反馈转发给您。尝试提交时，您将看到:invalid和:valid样式应用于表单控件。

自定义反馈样式将应用自定义颜色，边框，焦点样式和背景图标，以更好地传达反馈。背景图标<select>仅可用于.custom-select，而不能使用.form-control。

<form class="needs-validation" novalidate>
  <div class="form-row">
    <div class="col-md-6 mb-3">
      <label for="validationCustom01">First name</label>
      <input type="text" class="form-control" id="validationCustom01" value="Mark" required>
      <div class="valid-feedback">
        Looks good!
      </div>
    </div>
    <div class="col-md-6 mb-3">
      <label for="validationCustom02">Last name</label>
      <input type="text" class="form-control" id="validationCustom02" value="Otto" required>
      <div class="valid-feedback">
        Looks good!
      </div>
    </div>
  </div>
  <div class="form-row">
    <div class="col-md-6 mb-3">
      <label for="validationCustom03">City</label>
      <input type="text" class="form-control" id="validationCustom03" required>
      <div class="invalid-feedback">
        Please provide a valid city.
      </div>
    </div>
    <div class="col-md-3 mb-3">
      <label for="validationCustom04">State</label>
      <select class="custom-select" id="validationCustom04" required>
        <option selected disabled value="">Choose...</option>
        <option>...</option>
      </select>
      <div class="invalid-feedback">
        Please select a valid state.
      </div>
    </div>
    <div class="col-md-3 mb-3">
      <label for="validationCustom05">Zip</label>
      <input type="text" class="form-control" id="validationCustom05" required>
      <div class="invalid-feedback">
        Please provide a valid zip.
      </div>
    </div>
  </div>
  <div class="form-group">
    <div class="form-check">
      <input class="form-check-input" type="checkbox" value="" id="invalidCheck" required>
      <label class="form-check-label" for="invalidCheck">
        Agree to terms and conditions
      </label>
      <div class="invalid-feedback">
        You must agree before submitting.
      </div>
    </div>
  </div>
  <button class="btn btn-primary" type="submit">Submit form</button>
</form>

<script>
// Example starter JavaScript for disabling form submissions if there are invalid fields
(function() {
     
     
  'use strict';
  window.addEventListener('load', function() {
     
     
    // Fetch all the forms we want to apply custom Bootstrap validation styles to
    var forms = document.getElementsByClassName('needs-validation');
    // Loop over them and prevent submission
    var validation = Array.prototype.filter.call(forms, function(form) {
     
     
      form.addEventListener('submit', function(event) {
     
     
        if (form.checkValidity() === false) {
     
     
          event.preventDefault();
          event.stopPropagation();
        }
        form.classList.add('was-validated');
      }, false);
    });
  }, false);
})();
</script>

服务器端
我们建议使用客户端验证，但是如果您需要服务器端验证，则可以使用.is-invalid和指示无效和有效的表单字段.is-valid。请注意，.invalid-feedback这些类也支持。

对于无效字段，请使用来确保无效反馈/错误消息与相关表单字段相关联aria-describedby。id如果该字段已经指向其他表单文本，则此属性允许引用多个。

<form>
  <div class="form-row">
    <div class="col-md-6 mb-3">
      <label for="validationServer01">First name</label>
      <input type="text" class="form-control is-valid" id="validationServer01" value="Mark" required>
      <div class="valid-feedback">
        Looks good!
      </div>
    </div>
    <div class="col-md-6 mb-3">
      <label for="validationServer02">Last name</label>
      <input type="text" class="form-control is-valid" id="validationServer02" value="Otto" required>
      <div class="valid-feedback">
        Looks good!
      </div>
    </div>
  </div>
  <div class="form-row">
    <div class="col-md-6 mb-3">
      <label for="validationServer03">City</label>
      <input type="text" class="form-control is-invalid" id="validationServer03" aria-describedby="validationServer03Feedback" required>
      <div id="validationServer03Feedback" class="invalid-feedback">
        Please provide a valid city.
      </div>
    </div>
    <div class="col-md-3 mb-3">
      <label for="validationServer04">State</label>
      <select class="custom-select is-invalid" id="validationServer04" aria-describedby="validationServer04Feedback" required>
        <option selected disabled value="">Choose...</option>
        <option>...</option>
      </select>
      <div id="validationServer04Feedback" class="invalid-feedback">
        Please select a valid state.
      </div>
    </div>
    <div class="col-md-3 mb-3">
      <label for="validationServer05">Zip</label>
      <input type="text" class="form-control is-invalid" id="validationServer05" aria-describedby="validationServer05Feedback" required>
      <div id="validationServer05Feedback" class="invalid-feedback">
        Please provide a valid zip.
      </div>
    </div>
  </div>
  <div class="form-group">
    <div class="form-check">
      <input class="form-check-input is-invalid" type="checkbox" value="" id="invalidCheck3" aria-describedby="invalidCheck3Feedback" required>
      <label class="form-check-label" for="invalidCheck3">
        Agree to terms and conditions
      </label>
      <div  id="invalidCheck3Feedback" class="invalid-feedback">
        You must agree before submitting.
      </div>
    </div>
  </div>
  <button class="btn btn-primary" type="submit">Submit form</button>
</form>

支持的元素

验证样式可用于以下表单控件和组件：

• <input>和<textarea>与.form-control
• <select>与.form-control或.custom-select
• .form-checks
• .custom-checkboxs和.custom-radios
• .custom-file

<form class="was-validated">
  <div class="mb-3">
    <label for="validationTextarea">Textarea</label>
    <textarea class="form-control is-invalid" id="validationTextarea" placeholder="Required example textarea" required></textarea>
    <div class="invalid-feedback">
      Please enter a message in the textarea.
    </div>
  </div>

  <div class="custom-control custom-checkbox mb-3">
    <input type="checkbox" class="custom-control-input" id="customControlValidation1" required>
    <label class="custom-control-label" for="customControlValidation1">Check this custom checkbox</label>
    <div class="invalid-feedback">Example invalid feedback text</div>
  </div>

  <div class="custom-control custom-radio">
    <input type="radio" class="custom-control-input" id="customControlValidation2" name="radio-stacked" required>
    <label class="custom-control-label" for="customControlValidation2">Toggle this custom radio</label>
  </div>
  <div class="custom-control custom-radio mb-3">
    <input type="radio" class="custom-control-input" id="customControlValidation3" name="radio-stacked" required>
    <label class="custom-control-label" for="customControlValidation3">Or toggle this other custom radio</label>
    <div class="invalid-feedback">More example invalid feedback text</div>
  </div>

  <div class="mb-3">
    <select class="custom-select" required>
      <option value="">Choose...</option>
      <option value="1">One</option>
      <option value="2">Two</option>
      <option value="3">Three</option>
    </select>
    <div class="invalid-feedback">Example invalid custom select feedback</div>
  </div>

  <div class="custom-file mb-3">
    <input type="file" class="custom-file-input" id="validatedCustomFile" required>
    <label class="custom-file-label" for="validatedCustomFile">Choose file...</label>
    <div class="invalid-feedback">Example invalid custom file feedback</div>
  </div>

  <div class="mb-3">
    <div class="input-group is-invalid">
      <div class="input-group-prepend">
        <span class="input-group-text" id="validatedInputGroupPrepend">@</span>
      </div>
      <input type="text" class="form-control is-invalid" aria-describedby="validatedInputGroupPrepend" required>
    </div>
    <div class="invalid-feedback">
      Example invalid input group feedback
    </div>
  </div>

  <div class="mb-3">
    <div class="input-group is-invalid">
      <div class="input-group-prepend">
        <label class="input-group-text" for="validatedInputGroupSelect">Options</label>
      </div>
      <select class="custom-select" id="validatedInputGroupSelect" required>
        <option value="">Choose...</option>
        <option value="1">One</option>
        <option value="2">Two</option>
        <option value="3">Three</option>
      </select>
    </div>
    <div class="invalid-feedback">
      Example invalid input group feedback
    </div>
  </div>

  <div class="input-group is-invalid">
    <div class="custom-file">
      <input type="file" class="custom-file-input" id="validatedInputGroupCustomFile" required>
      <label class="custom-file-label" for="validatedInputGroupCustomFile">Choose file...</label>
    </div>
    <div class="input-group-append">
       <button class="btn btn-outline-secondary" type="button">Button</button>
    </div>
  </div>
  <div class="invalid-feedback">
    Example invalid input group feedback
  </div>
</form>

工具提示

如果您的表单布局允许，则可以将.{valid|invalid}-feedback类交换为.{valid|invalid}-tooltip类，以在样式化的工具提示中显示验证反馈。确保position: relative在其上放置父项以进行工具提示定位。在下面的示例中，我们的列类已经具有此功能，但是您的项目可能需要替代设置。

<form class="needs-validation" novalidate>
  <div class="form-row">
    <div class="col-md-6 mb-3">
      <label for="validationTooltip01">First name</label>
      <input type="text" class="form-control" id="validationTooltip01" value="Mark" required>
      <div class="valid-tooltip">
        Looks good!
      </div>
    </div>
    <div class="col-md-6 mb-3">
      <label for="validationTooltip02">Last name</label>
      <input type="text" class="form-control" id="validationTooltip02" value="Otto" required>
      <div class="valid-tooltip">
        Looks good!
      </div>
    </div>
  </div>
  <div class="form-row">
    <div class="col-md-6 mb-3">
      <label for="validationTooltip03">City</label>
      <input type="text" class="form-control" id="validationTooltip03" required>
      <div class="invalid-tooltip">
        Please provide a valid city.
      </div>
    </div>
    <div class="col-md-3 mb-3">
      <label for="validationTooltip04">State</label>
      <select class="custom-select" id="validationTooltip04" required>
        <option selected disabled value="">Choose...</option>
        <option>...</option>
      </select>
      <div class="invalid-tooltip">
        Please select a valid state.
      </div>
    </div>
    <div class="col-md-3 mb-3">
      <label for="validationTooltip05">Zip</label>
      <input type="text" class="form-control" id="validationTooltip05" required>
      <div class="invalid-tooltip">
        Please provide a valid zip.
      </div>
    </div>
  </div>
  <button class="btn btn-primary" type="submit">Submit form</button>
</form>

开关

开关具有自定义复选框的标记，但是使用.custom-switch该类来呈现切换开关。开关也支持该disabled属性。

<div class="custom-control custom-switch">
  <input type="checkbox" class="custom-control-input" id="customSwitch1">
  <label class="custom-control-label" for="customSwitch1">Toggle this switch element</label>
</div>
<div class="custom-control custom-switch">
  <input type="checkbox" class="custom-control-input" disabled id="customSwitch2">
  <label class="custom-control-label" for="customSwitch2">Disabled switch element</label>
</div>

选择菜单

自定义<select>菜单仅需要一个自定义类.custom-select即可触发自定义样式。自定义样式仅限于<select>的初始外观，<option>由于浏览器的限制，无法修改。

<select class="custom-select">
  <option selected>打开此选择菜单</option>
  <option value="1">One</option>
  <option value="2">Two</option>
  <option value="3">Three</option>
</select>

大小

<select class="custom-select custom-select-lg mb-3">
  <option selected>Open this select menu</option>
  <option value="1">One</option>
  <option value="2">Two</option>
  <option value="3">Three</option>
</select>

<select class="custom-select custom-select-sm">
  <option selected>Open this select menu</option>
  <option value="1">One</option>
  <option value="2">Two</option>
  <option value="3">Three</option>
</select>

multiple还支持该属性：

<select class="custom-select" multiple>
  <option selected>Open this select menu</option>
  <option value="1">One</option>
  <option value="2">Two</option>
  <option value="3">Three</option>
</select>

作为size属性：

<select class="custom-select" size="3">
  <option selected>Open this select menu</option>
  <option value="1">One</option>
  <option value="2">Two</option>
  <option value="3">Three</option>
</select>

范围

创建自定义<input type="range">与控制.custom-range。轨道（背景）和拇指（值）的样式都在浏览器中显示为相同。由于只有IE和Firefox支持从拇指的左侧或右侧“填充”其轨迹，以可视方式指示进度，因此我们目前不支持它。

文件浏览器

推荐使用动画制作自定义文件输入的插件：bs-custom-file-input

<div class="custom-file">
  <input type="file" class="custom-file-input" id="customFile">
  <label class="custom-file-label" for="customFile">选择文件</label>
</div>

输入组

通过在文本输入，自定义选择和自定义文件输入的两侧添加文本，按钮或按钮组，可以轻松扩展表单控件。
将一个附加组件或按钮放在输入的两侧。您也可以在输入的两侧放置一个。记住将<label>放在输入组之外。

<div class="input-group mb-3">
  <div class="input-group-prepend">
    <span class="input-group-text" id="basic-addon1">@</span>
  </div>
  <input type="text" class="form-control" placeholder="Username" aria-label="Username" aria-describedby="basic-addon1">
</div>

<div class="input-group mb-3">
  <input type="text" class="form-control" placeholder="Recipient's username" aria-label="Recipient's username" aria-describedby="basic-addon2">
  <div class="input-group-append">
    <span class="input-group-text" id="basic-addon2">@example.com</span>
  </div>
</div>

<label for="basic-url">Your vanity URL</label>
<div class="input-group mb-3">
  <div class="input-group-prepend">
    <span class="input-group-text" id="basic-addon3">https://example.com/users/</span>
  </div>
  <input type="text" class="form-control" id="basic-url" aria-describedby="basic-addon3">
</div>

<div class="input-group mb-3">
  <div class="input-group-prepend">
    <span class="input-group-text">$</span>
  </div>
  <input type="text" class="form-control" aria-label="Amount (to the nearest dollar)">
  <div class="input-group-append">
    <span class="input-group-text">.00</span>
  </div>
</div>

<div class="input-group">
  <div class="input-group-prepend">
    <span class="input-group-text">With textarea</span>
  </div>
  <textarea class="form-control" aria-label="With textarea"></textarea>
</div>

默认情况下，输入组会通过包装，flex-wrap: wrap以适应输入组中的自定义表单字段验证。您可以使用禁用此功能.flex-nowrap。

<div class="input-group flex-nowrap">
  <div class="input-group-prepend">
    <span class="input-group-text" id="addon-wrapping">@</span>
  </div>
  <input type="text" class="form-control" placeholder="Username" aria-label="Username" aria-describedby="addon-wrapping">
</div>

大小

<div class="input-group input-group-sm mb-3">
  <div class="input-group-prepend">
    <span class="input-group-text" id="inputGroup-sizing-sm">Small</span>
  </div>
  <input type="text" class="form-control" aria-label="Sizing example input" aria-describedby="inputGroup-sizing-sm">
</div>

<div class="input-group mb-3">
  <div class="input-group-prepend">
    <span class="input-group-text" id="inputGroup-sizing-default">Default</span>
  </div>
  <input type="text" class="form-control" aria-label="Sizing example input" aria-describedby="inputGroup-sizing-default">
</div>

<div class="input-group input-group-lg">
  <div class="input-group-prepend">
    <span class="input-group-text" id="inputGroup-sizing-lg">Large</span>
  </div>
  <input type="text" class="form-control" aria-label="Sizing example input" aria-describedby="inputGroup-sizing-lg">
</div>

复选框和单选框

将任何复选框或单选选项放在输入组的插件中，而不是文本中。

<div class="input-group mb-3">
  <div class="input-group-prepend">
    <div class="input-group-text">
      <input type="checkbox" aria-label="Checkbox for following text input">
    </div>
  </div>
  <input type="text" class="form-control" aria-label="Text input with checkbox">
</div>

<div class="input-group">
  <div class="input-group-prepend">
    <div class="input-group-text">
      <input type="radio" aria-label="Radio button for following text input">
    </div>
  </div>
  <input type="text" class="form-control" aria-label="Text input with radio button">
</div>

多个插件

支持多个加载项，并且可以与复选框和广播输入版本混合使用。

<div class="input-group mb-3">
  <div class="input-group-prepend">
    <span class="input-group-text">$</span>
    <span class="input-group-text">0.00</span>
  </div>
  <input type="text" class="form-control" aria-label="Dollar amount (with dot and two decimal places)">
</div>

<div class="input-group">
  <input type="text" class="form-control" aria-label="Dollar amount (with dot and two decimal places)">
  <div class="input-group-append">
    <span class="input-group-text">$</span>
    <span class="input-group-text">0.00</span>
  </div>
</div>

按钮

<div class="input-group mb-3">
  <div class="input-group-prepend">
    <button class="btn btn-outline-secondary" type="button" id="button-addon1">Button</button>
  </div>
  <input type="text" class="form-control" placeholder="" aria-label="Example text with button addon" aria-describedby="button-addon1">
</div>

<div class="input-group mb-3">
  <input type="text" class="form-control" placeholder="Recipient's username" aria-label="Recipient's username" aria-describedby="button-addon2">
  <div class="input-group-append">
    <button class="btn btn-outline-secondary" type="button" id="button-addon2">Button</button>
  </div>
</div>

<div class="input-group mb-3">
  <div class="input-group-prepend" id="button-addon3">
    <button class="btn btn-outline-secondary" type="button">Button</button>
    <button class="btn btn-outline-secondary" type="button">Button</button>
  </div>
  <input type="text" class="form-control" placeholder="" aria-label="Example text with two button addons" aria-describedby="button-addon3">
</div>

<div class="input-group">
  <input type="text" class="form-control" placeholder="Recipient's username" aria-label="Recipient's username with two button addons" aria-describedby="button-addon4">
  <div class="input-group-append" id="button-addon4">
    <button class="btn btn-outline-secondary" type="button">Button</button>
    <button class="btn btn-outline-secondary" type="button">Button</button>
  </div>
</div>

带有下拉菜单的按钮

<div class="input-group mb-3">
  <div class="input-group-prepend">
    <button class="btn btn-outline-secondary dropdown-toggle" type="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">Dropdown</button>
    <div class="dropdown-menu">
      <a class="dropdown-item" href="#">Action</a>
      <a class="dropdown-item" href="#">Another action</a>
      <a class="dropdown-item" href="#">Something else here</a>
      <div role="separator" class="dropdown-divider"></div>
      <a class="dropdown-item" href="#">Separated link</a>
    </div>
  </div>
  <input type="text" class="form-control" aria-label="Text input with dropdown button">
</div>

<div class="input-group">
  <input type="text" class="form-control" aria-label="Text input with dropdown button">
  <div class="input-group-append">
    <button class="btn btn-outline-secondary dropdown-toggle" type="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">Dropdown</button>
    <div class="dropdown-menu">
      <a class="dropdown-item" href="#">Action</a>
      <a class="dropdown-item" href="#">Another action</a>
      <a class="dropdown-item" href="#">Something else here</a>
      <div role="separator" class="dropdown-divider"></div>
      <a class="dropdown-item" href="#">Separated link</a>
    </div>
  </div>
</div>

分段按钮

<div class="input-group mb-3">
  <div class="input-group-prepend">
    <button type="button" class="btn btn-outline-secondary">Action</button>
    <button type="button" class="btn btn-outline-secondary dropdown-toggle dropdown-toggle-split" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
      <span class="sr-only">Toggle Dropdown</span>
    </button>
    <div class="dropdown-menu">
      <a class="dropdown-item" href="#">Action</a>
      <a class="dropdown-item" href="#">Another action</a>
      <a class="dropdown-item" href="#">Something else here</a>
      <div role="separator" class="dropdown-divider"></div>
      <a class="dropdown-item" href="#">Separated link</a>
    </div>
  </div>
  <input type="text" class="form-control" aria-label="Text input with segmented dropdown button">
</div>

<div class="input-group">
  <input type="text" class="form-control" aria-label="Text input with segmented dropdown button">
  <div class="input-group-append">
    <button type="button" class="btn btn-outline-secondary">Action</button>
    <button type="button" class="btn btn-outline-secondary dropdown-toggle dropdown-toggle-split" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
      <span class="sr-only">Toggle Dropdown</span>
    </button>
    <div class="dropdown-menu">
      <a class="dropdown-item" href="#">Action</a>
      <a class="dropdown-item" href="#">Another action</a>
      <a class="dropdown-item" href="#">Something else here</a>
      <div role="separator" class="dropdown-divider"></div>
      <a class="dropdown-item" href="#">Separated link</a>
    </div>
  </div>
</div>

自订表格
输入组包括对自定义选择和自定义文件输入的支持。不支持这些浏览器的默认版本。

<div class="input-group mb-3">
  <div class="input-group-prepend">
    <label class="input-group-text" for="inputGroupSelect01">Options</label>
  </div>
  <select class="custom-select" id="inputGroupSelect01">
    <option selected>Choose...</option>
    <option value="1">One</option>
    <option value="2">Two</option>
    <option value="3">Three</option>
  </select>
</div>

<div class="input-group mb-3">
  <select class="custom-select" id="inputGroupSelect02">
    <option selected>Choose...</option>
    <option value="1">One</option>
    <option value="2">Two</option>
    <option value="3">Three</option>
  </select>
  <div class="input-group-append">
    <label class="input-group-text" for="inputGroupSelect02">Options</label>
  </div>
</div>

<div class="input-group mb-3">
  <div class="input-group-prepend">
    <button class="btn btn-outline-secondary" type="button">Button</button>
  </div>
  <select class="custom-select" id="inputGroupSelect03" aria-label="Example select with button addon">
    <option selected>Choose...</option>
    <option value="1">One</option>
    <option value="2">Two</option>
    <option value="3">Three</option>
  </select>
</div>

<div class="input-group">
  <select class="custom-select" id="inputGroupSelect04" aria-label="Example select with button addon">
    <option selected>Choose...</option>
    <option value="1">One</option>
    <option value="2">Two</option>
    <option value="3">Three</option>
  </select>
  <div class="input-group-append">
    <button class="btn btn-outline-secondary" type="button">Button</button>
  </div>
</div>

自定义文件输入

<div class="input-group mb-3">
  <div class="input-group-prepend">
    <span class="input-group-text" id="inputGroupFileAddon01">Upload</span>
  </div>
  <div class="custom-file">
    <input type="file" class="custom-file-input" id="inputGroupFile01" aria-describedby="inputGroupFileAddon01">
    <label class="custom-file-label" for="inputGroupFile01">Choose file</label>
  </div>
</div>

<div class="input-group mb-3">
  <div class="custom-file">
    <input type="file" class="custom-file-input" id="inputGroupFile02">
    <label class="custom-file-label" for="inputGroupFile02" aria-describedby="inputGroupFileAddon02">Choose file</label>
  </div>
  <div class="input-group-append">
    <span class="input-group-text" id="inputGroupFileAddon02">Upload</span>
  </div>
</div>

<div class="input-group mb-3">
  <div class="input-group-prepend">
    <button class="btn btn-outline-secondary" type="button" id="inputGroupFileAddon03">Button</button>
  </div>
  <div class="custom-file">
    <input type="file" class="custom-file-input" id="inputGroupFile03" aria-describedby="inputGroupFileAddon03">
    <label class="custom-file-label" for="inputGroupFile03">Choose file</label>
  </div>
</div>

<div class="input-group">
  <div class="custom-file">
    <input type="file" class="custom-file-input" id="inputGroupFile04" aria-describedby="inputGroupFileAddon04">
    <label class="custom-file-label" for="inputGroupFile04">Choose file</label>
  </div>
  <div class="input-group-append">
    <button class="btn btn-outline-secondary" type="button" id="inputGroupFileAddon04">Button</button>
  </div>
</div>

大屏幕

轻巧灵活的组件，用于展示英雄单位风格的内容。

<div class="jumbotron">
  <h1 class="display-4">你好，世界！</h1>
  <p class="lead">这是一个简单的英雄单元，是一个简单的巨无霸风格的组件，可以引起人们对特色内容或信息的更多关注。</p>
  <hr class="my-4">
  <p>它使用实用程序类来进行排版和间距，以在较大的容器内分隔内容。
</p>
  <a class="btn btn-primary btn-lg" href="#" role="button">了解更多</a>
</div>

要使超长距伞成为全角且没有圆角，请添加.jumbotron-fluid修饰符类并在其中添加.container或.container-fluid。

<div class="jumbotron jumbotron-fluid">
  <div class="container">
    <h1 class="display-4">Fluid jumbotron</h1>
    <p class="lead">This is a modified jumbotron that occupies the entire horizontal space of its parent.</p>
  </div>
</div>

列表组

列表组是用于显示一系列内容的灵活而强大的组件。修改并扩展它们以支持其中的几乎所有内容。

<ul class="list-group">
  <li class="list-group-item">Cras justo odio</li>
  <li class="list-group-item">Dapibus ac facilisis in</li>
  <li class="list-group-item">Morbi leo risus</li>
  <li class="list-group-item">Porta ac consectetur ac</li>
  <li class="list-group-item">Vestibulum at eros</li>
</ul>

添加.active到.list-group-item以指示当前的活动选择。

<ul class="list-group">
  <li class="list-group-item active">Cras justo odio</li>
  <li class="list-group-item">Dapibus ac facilisis in</li>
  <li class="list-group-item">Morbi leo risus</li>
  <li class="list-group-item">Porta ac consectetur ac</li>
  <li class="list-group-item">Vestibulum at eros</li>
</ul>

添加.disabled到.list-group-item使其显示为禁用状态。请注意，带有的某些元素.disabled还需要自定义JavaScript才能完全禁用其点击事件（例如，链接）。

链接和按钮

使用<a>或，通过添加<button>来创建具有悬浮，禁用和活动状态的可操作列表组项目.list-group-item-action。

<div class="list-group">
  <a href="#" class="list-group-item list-group-item-action active">
    Cras justo odio
  </a>
  <a href="#" class="list-group-item list-group-item-action">Dapibus ac facilisis in</a>
  <a href="#" class="list-group-item list-group-item-action">Morbi leo risus</a>
  <a href="#" class="list-group-item list-group-item-action">Porta ac consectetur ac</a>
  <a href="#" class="list-group-item list-group-item-action disabled" tabindex="-1" aria-disabled="true">Vestibulum at eros</a>
</div>

添加.list-group-flush以删除某些边框和圆角，以在父容器（例如卡片）中边对边呈现列表组项。

<ul class="list-group list-group-flush">
  <li class="list-group-item">Cras justo odio</li>
  <li class="list-group-item">Dapibus ac facilisis in</li>
  <li class="list-group-item">Morbi leo risus</li>
  <li class="list-group-item">Porta ac consectetur ac</li>
  <li class="list-group-item">Vestibulum at eros</li>
</ul>

添加.list-group-horizontal以将所有断点的列表组项目的布局从垂直更改为水平。或者，选择一个响应变体.list-group-horizontal-{sm|md|lg|xl}以使列表组从该断点开始为水平min-width。当前水平列表组不能与刷新列表组结合。

<ul class="list-group list-group-horizontal">
  <li class="list-group-item">Cras justo odio</li>
  <li class="list-group-item">Dapibus ac facilisis in</li>
  <li class="list-group-item"/>Morbi leo risus</li>
</ul>

<ul class="list-group list-group-horizontal-sm">
  <li class="list-group-item">Cras justo odio</li>
  <li class="list-group-item">Dapibus ac facilisis in</li>
  <li class="list-group-item">Morbi leo risus</li>
</ul>

<ul class="list-group list-group-horizontal-md">
  <li class="list-group-item">Cras justo odio</li>
  <li class="list-group-item">Dapibus ac facilisis in</li>
  <li class="list-group-item">Morbi leo risus</li>
</ul>

<ul class="list-group list-group-horizontal-lg">
  <li class="list-group-item">Cras justo odio</li>
  <li class="list-group-item">Dapibus ac facilisis in</li>
  <li class="list-group-item">Morbi leo risus</li>
</ul>

<ul class="list-group list-group-horizontal-xl">
  <li class="list-group-item">Cras justo odio</li>
  <li class="list-group-item">Dapibus ac facilisis in</li>
  <li class="list-group-item">Morbi leo risus</li>
</ul>

上下文类

使用上下文类为具有状态背景和颜色的列表项设置样式。

<ul class="list-group">
  <li class="list-group-item">Dapibus ac facilisis in</li>

  
  <li class="list-group-item list-group-item-primary">A simple primary list group item</li>
  <li class="list-group-item list-group-item-secondary">A simple secondary list group item</li>
  <li class="list-group-item list-group-item-success">A simple success list group item</li>
  <li class="list-group-item list-group-item-danger">A simple danger list group item</li>
  <li class="list-group-item list-group-item-warning">A simple warning list group item</li>
  <li class="list-group-item list-group-item-info">A simple info list group item</li>
  <li class="list-group-item list-group-item-light">A simple light list group item</li>
  <li class="list-group-item list-group-item-dark">A simple dark list group item</li>
</ul>

带徽章

在某些实用程序的帮助下，将标志添加到任何列表组项以显示未读计数，活动等。

<ul class="list-group">
  <li class="list-group-item d-flex justify-content-between align-items-center">
    Cras justo odio
    <span class="badge badge-primary badge-pill">14</span>
  </li>
  <li class="list-group-item d-flex justify-content-between align-items-center">
    Dapibus ac facilisis in
    <span class="badge badge-primary badge-pill">2</span>
  </li>
  <li class="list-group-item d-flex justify-content-between align-items-center">
    Morbi leo risus
    <span class="badge badge-primary badge-pill">1</span>
  </li>
</ul>

自订内容

借助flexbox实用程序，几乎可以在其中添加所有HTML，甚至可以为下面的链接列表组添加HTML 。

<div class="list-group">
  <a href="#" class="list-group-item list-group-item-action active">
    <div class="d-flex w-100 justify-content-between">
      <h5 class="mb-1">List group item heading</h5>
      <small>3 days ago</small>
    </div>
    <p class="mb-1">Donec id elit non mi porta gravida at eget metus. Maecenas sed diam eget risus varius blandit.</p>
    <small>Donec id elit non mi porta.</small>
  </a>
  <a href="#" class="list-group-item list-group-item-action">
    <div class="d-flex w-100 justify-content-between">
      <h5 class="mb-1">List group item heading</h5>
      <small class="text-muted">3 days ago</small>
    </div>
    <p class="mb-1">Donec id elit non mi porta gravida at eget metus. Maecenas sed diam eget risus varius blandit.</p>
    <small class="text-muted">Donec id elit non mi porta.</small>
  </a>
  <a href="#" class="list-group-item list-group-item-action">
    <div class="d-flex w-100 justify-content-between">
      <h5 class="mb-1">List group item heading</h5>
      <small class="text-muted">3 days ago</small>
    </div>
    <p class="mb-1">Donec id elit non mi porta gravida at eget metus. Maecenas sed diam eget risus varius blandit.</p>
    <small class="text-muted">Donec id elit non mi porta.</small>
  </a>
</div>

使用选项卡JavaScript插件（单独包含它或通过编译的bootstrap.js文件包含它）来扩展列表组，以创建本地内容的可选项窗格。

<div class="row">
  <div class="col-4">
    <div class="list-group" id="list-tab" role="tablist">
      <a class="list-group-item list-group-item-action active" id="list-home-list" data-toggle="list" href="#list-home" role="tab" aria-controls="home">Home</a>
      <a class="list-group-item list-group-item-action" id="list-profile-list" data-toggle="list" href="#list-profile" role="tab" aria-controls="profile">Profile</a>
      <a class="list-group-item list-group-item-action" id="list-messages-list" data-toggle="list" href="#list-messages" role="tab" aria-controls="messages">Messages</a>
      <a class="list-group-item list-group-item-action" id="list-settings-list" data-toggle="list" href="#list-settings" role="tab" aria-controls="settings">Settings</a>
    </div>
  </div>
  <div class="col-8">
    <div class="tab-content" id="nav-tabContent">
      <div class="tab-pane fade show active" id="list-home" role="tabpanel" aria-labelledby="list-home-list">...</div>
      <div class="tab-pane fade" id="list-profile" role="tabpanel" aria-labelledby="list-profile-list">...</div>
      <div class="tab-pane fade" id="list-messages" role="tabpanel" aria-labelledby="list-messages-list">...</div>
      <div class="tab-pane fade" id="list-settings" role="tabpanel" aria-labelledby="list-settings-list">...</div>
    </div>
  </div>
</div>

只需指定data-toggle="list"或在元素上即可激活列表组导航而无需编写任何JavaScript 。在上使用这些数据属性.list-group-item。

<!-- List group -->
<div class="list-group" id="myList" role="tablist">
  <a class="list-group-item list-group-item-action active" data-toggle="list" href="#home" role="tab">Home</a>
  <a class="list-group-item list-group-item-action" data-toggle="list" href="#profile" role="tab">Profile</a>
  <a class="list-group-item list-group-item-action" data-toggle="list" href="#messages" role="tab">Messages</a>
  <a class="list-group-item list-group-item-action" data-toggle="list" href="#settings" role="tab">Settings</a>
</div>

<!-- Tab panes -->
<div class="tab-content">
  <div class="tab-pane active" id="home" role="tabpanel">...</div>
  <div class="tab-pane" id="profile" role="tabpanel">...</div>
  <div class="tab-pane" id="messages" role="tabpanel">...</div>
  <div class="tab-pane" id="settings" role="tabpanel">...</div>
</div>

通过JavaScript启用可选项列表项（每个列表项需要单独激活）：

$('#myList a').on('click', function (e) {
  e.preventDefault()
  $(this).tab('show')
})

您可以通过以下几种方式激活单个列表项：

$('#myList a[href="#profile"]').tab('show') // Select tab by name
$('#myList a:first-child').tab('show') // Select first tab
$('#myList a:last-child').tab('show') // Select last tab
$('#myList a:nth-child(3)').tab('show') // Select third tab

淡入淡出效果
要使选项卡面板淡入，请添加.fade到每个.tab-pane。第一个选项卡窗格还必须.show使初始内容可见。

<div class="tab-content">
  <div class="tab-pane fade show active" id="home" role="tabpanel">...</div>
  <div class="tab-pane fade" id="profile" role="tabpanel">...</div>
  <div class="tab-pane fade" id="messages" role="tabpanel">...</div>
  <div class="tab-pane fade" id="settings" role="tabpanel">...</div>
</div>

方法

$().tab
激活列表项元素和内容容器。Tab应该在DOM中具有data-target或href定位容器节点。

<div class="list-group" id="myList" role="tablist">
  <a class="list-group-item list-group-item-action active" data-toggle="list" href="#home" role="tab">Home</a>
  <a class="list-group-item list-group-item-action" data-toggle="list" href="#profile" role="tab">Profile</a>
  <a class="list-group-item list-group-item-action" data-toggle="list" href="#messages" role="tab">Messages</a>
  <a class="list-group-item list-group-item-action" data-toggle="list" href="#settings" role="tab">Settings</a>
</div>

<div class="tab-content">
  <div class="tab-pane active" id="home" role="tabpanel">...</div>
  <div class="tab-pane" id="profile" role="tabpanel">...</div>
  <div class="tab-pane" id="messages" role="tabpanel">...</div>
  <div class="tab-pane" id="settings" role="tabpanel">...</div>
</div>

<script>
  $(function () {
     
     
    $('#myList a:last-child').tab('show')
  })
</script>

.tab(‘show’)
选择给定的列表项并显示其关联的窗格。先前选择的任何其他列表项将变为未选中状态，并且其关联的窗格被隐藏。在实际显示选项卡窗格之前（例如，在shown.bs.tab事件发生之前）返回到调用者。

$('#someListItem').tab('show')

事记

显示新标签时，事件将按以下顺序触发：

1. hide.bs.tab （在当前活动标签上）
2. show.bs.tab（在待显示的标签上）
3. hidden.bs.tab（在上一个活动选项卡上，与活动相同hide.bs.tab）
4. shown.bs.tab（在刚刚显示的新活动标签上，该标签与该show.bs.tab活动的标签相同）

如果尚未激活任何选项卡，则不会触发hide.bs.tab和hidden.bs.tab事件。

$('a[data-toggle="list"]').on('shown.bs.tab', function (e) {
  e.target // newly activated tab
  e.relatedTarget // previous active tab
})

媒体对象

Bootstrap媒体对象的文档和示例，用于构建高度重复的组件，例如博客评论，推文等。

<div class="media">
  <img src="..." class="mr-3" alt="...">
  <div class="media-body">
    <h5 class="mt-0">Media heading</h5>
    Cras sit amet nibh libero, in gravida nulla. Nulla vel metus scelerisque ante sollicitudin. Cras purus odio, vestibulum in vulputate at, tempus viverra turpis. Fusce condimentum nunc ac nisi vulputate fringilla. Donec lacinia congue felis in faucibus.
  </div>
</div>

嵌套

媒体对象可以无限嵌套，尽管我们建议您在某个时候停止。嵌套.media在.media-body父媒体对象的中。

<div class="media">
  <img src="..." class="mr-3" alt="...">
  <div class="media-body">
    <h5 class="mt-0">Media heading</h5>
    Cras sit amet nibh libero, in gravida nulla. Nulla vel metus scelerisque ante sollicitudin. Cras purus odio, vestibulum in vulputate at, tempus viverra turpis. Fusce condimentum nunc ac nisi vulputate fringilla. Donec lacinia congue felis in faucibus.

    <div class="media mt-3">
      <a class="mr-3" href="#">
        <img src="..." class="mr-3" alt="...">
      </a>
      <div class="media-body">
        <h5 class="mt-0">Media heading</h5>
        Cras sit amet nibh libero, in gravida nulla. Nulla vel metus scelerisque ante sollicitudin. Cras purus odio, vestibulum in vulputate at, tempus viverra turpis. Fusce condimentum nunc ac nisi vulputate fringilla. Donec lacinia congue felis in faucibus.
      </div>
    </div>
  </div>
</div>

对齐

媒体对象中的媒体可以使用Flexbox实用程序对齐到内容的顶部（默认），中间或结尾.media-body。
顶对齐

<div class="media">
  <img src="..." class="align-self-start mr-3" alt="...">
  <div class="media-body">
    <h5 class="mt-0">Top-aligned media</h5>
    <p>Cras sit amet nibh libero, in gravida nulla. Nulla vel metus scelerisque ante sollicitudin. Cras purus odio, vestibulum in vulputate at, tempus viverra turpis. Fusce condimentum nunc ac nisi vulputate fringilla. Donec lacinia congue felis in faucibus.</p>
    <p>Donec sed odio dui. Nullam quis risus eget urna mollis ornare vel eu leo. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus.</p>
  </div>
</div>

居中对齐

<div class="media">
  <img src="..." class="align-self-center mr-3" alt="...">
  <div class="media-body">
    <h5 class="mt-0">Center-aligned media</h5>
    <p>Cras sit amet nibh libero, in gravida nulla. Nulla vel metus scelerisque ante sollicitudin. Cras purus odio, vestibulum in vulputate at, tempus viverra turpis. Fusce condimentum nunc ac nisi vulputate fringilla. Donec lacinia congue felis in faucibus.</p>
    <p class="mb-0">Donec sed odio dui. Nullam quis risus eget urna mollis ornare vel eu leo. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus.</p>
  </div>
</div>

底对齐

<div class="media">
  <img src="..." class="align-self-end mr-3" alt="...">
  <div class="media-body">
    <h5 class="mt-0">Bottom-aligned media</h5>
    <p>Cras sit amet nibh libero, in gravida nulla. Nulla vel metus scelerisque ante sollicitudin. Cras purus odio, vestibulum in vulputate at, tempus viverra turpis. Fusce condimentum nunc ac nisi vulputate fringilla. Donec lacinia congue felis in faucibus.</p>
    <p class="mb-0">Donec sed odio dui. Nullam quis risus eget urna mollis ornare vel eu leo. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus.</p>
  </div>
</div>

调整
通过修改HTML本身或添加一些自定义flexbox CSS来设置order属性（更改为您选择的整数），可以更改媒体对象中内容的顺序。

<div class="media">
  <div class="media-body">
    <h5 class="mt-0 mb-1">Media object</h5>
    Cras sit amet nibh libero, in gravida nulla. Nulla vel metus scelerisque ante sollicitudin. Cras purus odio, vestibulum in vulputate at, tempus viverra turpis. Fusce condimentum nunc ac nisi vulputate fringilla. Donec lacinia congue felis in faucibus.
  </div>
  <img src="..." class="ml-3" alt="...">
</div>

媒体列表

由于媒体对象的结构要求很少，因此您也可以在列表HTML元素上使用这些类。在您<ul>或者<ol>，添加.list-unstyled删除任何浏览器的默认列表样式，然后应用.media到你的<li>秒。与往常一样，在需要微调的地方都使用间距实用程序。

<ul class="list-unstyled">
  <li class="media">
    <img src="..." class="mr-3" alt="...">
    <div class="media-body">
      <h5 class="mt-0 mb-1">List-based media object</h5>
      Cras sit amet nibh libero, in gravida nulla. Nulla vel metus scelerisque ante sollicitudin. Cras purus odio, vestibulum in vulputate at, tempus viverra turpis. Fusce condimentum nunc ac nisi vulputate fringilla. Donec lacinia congue felis in faucibus.
    </div>
  </li>
  <li class="media my-4">
    <img src="..." class="mr-3" alt="...">
    <div class="media-body">
      <h5 class="mt-0 mb-1">List-based media object</h5>
      Cras sit amet nibh libero, in gravida nulla. Nulla vel metus scelerisque ante sollicitudin. Cras purus odio, vestibulum in vulputate at, tempus viverra turpis. Fusce condimentum nunc ac nisi vulputate fringilla. Donec lacinia congue felis in faucibus.
    </div>
  </li>
  <li class="media">
    <img src="..." class="mr-3" alt="...">
    <div class="media-body">
      <h5 class="mt-0 mb-1">List-based media object</h5>
      Cras sit amet nibh libero, in gravida nulla. Nulla vel metus scelerisque ante sollicitudin. Cras purus odio, vestibulum in vulputate at, tempus viverra turpis. Fusce condimentum nunc ac nisi vulputate fringilla. Donec lacinia congue felis in faucibus.
    </div>
  </li>
</ul>

模态框

使用Bootstrap的JavaScript模式插件将对话框添加到您的网站，以获取灯箱，用户通知或完全自定义的内容。
原理:

• 使用HTML，CSS和JavaScript构建模态。它们位于文档的其他所有内容上，并从中移除滚动，从而使模式内容滚动。
• 单击模式“背景”将自动关闭模式。
• Bootstrap一次仅支持一个模式窗口。不支持嵌套模式，因为我们认为它们是糟糕的用户体验。
• 模态使用position: fixed，有时可能对其渲染有些特殊。尽可能将模式HTML放在顶级位置，以避免其他元素的潜在干扰。.modal在另一个固定元素中嵌套时，您可能会遇到问题。
• 同样，由于position: fixed，在移动设备上使用模态有一些警告。有关详细信息，请参见我们的浏览器支持文档。
• 由于HTML5如何定义其语义，因此autofocusHTML属性在Bootstrap模态中无效。为了达到相同的效果，请使用一些自定义JavaScript：

$('#myModal').on('shown.bs.modal', function () {
  $('#myInput').trigger('focus')
})

模态组件

下面是一个静态模态示例（表示其position和display已被覆盖）。包括模态页眉，模态主体（必需padding）和模态页脚（可选）。我们要求您在可能的情况下在模式标头中包含dismiss操作，或提供另一个显式的dismiss操作。

<div class="modal" tabindex="-1">
  <div class="modal-dialog">
    <div class="modal-content">
      <div class="modal-header">
        <h5 class="modal-title">Modal title</h5>
        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
          <span aria-hidden="true">&times;</span>
        </button>
      </div>
      <div class="modal-body">
        <p>Modal body text goes here.</p>
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
        <button type="button" class="btn btn-primary">Save changes</button>
      </div>
    </div>
  </div>
</div>

<!-- Button trigger modal -->
<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal">
  Launch demo modal
</button>

<!-- Modal -->
<div class="modal fade" id="exampleModal" tabindex="-1" aria-labelledby="exampleModalLabel" aria-hidden="true">
  <div class="modal-dialog">
    <div class="modal-content">
      <div class="modal-header">
        <h5 class="modal-title" id="exampleModalLabel">Modal title</h5>
        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
          <span aria-hidden="true">&times;</span>
        </button>
      </div>
      <div class="modal-body">
        ...
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
        <button type="button" class="btn btn-primary">Save changes</button>
      </div>
    </div>
  </div>
</div>

当背景设置为静态时，在其外部单击时，模式不会关闭。单击下面的按钮尝试。

<!-- Button trigger modal -->
<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#staticBackdrop">
  Launch static backdrop modal
</button>

<!-- Modal -->
<div class="modal fade" id="staticBackdrop" data-backdrop="static" data-keyboard="false" tabindex="-1" aria-labelledby="staticBackdropLabel" aria-hidden="true">
  <div class="modal-dialog">
    <div class="modal-content">
      <div class="modal-header">
        <h5 class="modal-title" id="staticBackdropLabel">Modal title</h5>
        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
          <span aria-hidden="true">&times;</span>
        </button>
      </div>
      <div class="modal-body">
        ...
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
        <button type="button" class="btn btn-primary">Understood</button>
      </div>
    </div>
  </div>
</div>

滚动长内容

可以创建一个可滚动的模式，允许通过添加滚动模式的身体.modal-dialog-scrollable到.modal-dialog

<!-- Scrollable modal -->
<div class="modal-dialog modal-dialog-scrollable">
  ...
</div>

垂直居中
将模态添加.modal-dialog-centered到.modal-dialog垂直居中。

<!-- Vertically centered modal -->
<div class="modal-dialog modal-dialog-centered">
  ...
</div>

<!-- Vertically centered scrollable modal -->
<div class="modal-dialog modal-dialog-centered modal-dialog-scrollable">
  ...
</div>

工具提示和弹出窗口

可以根据需要将工具提示和弹出窗口放置在模态中。关闭模态后，其中的所有工具提示和弹出窗口也将自动关闭。

<div class="modal-body">
  <h5>Popover in a modal</h5>
  <p>This <a href="#" role="button" class="btn btn-secondary popover-test" title="Popover title" data-content="Popover body content is set in this attribute.">button</a> triggers a popover on click.</p>
  <hr>
  <h5>Tooltips in a modal</h5>
  <p><a href="#" class="tooltip-test" title="Tooltip">This link</a> and <a href="#" class="tooltip-test" title="Tooltip">that link</a> have tooltips on hover.</p>
</div>

使用网格

通过嵌套.container-fluid在模态中利用Bootstrap网格系统.modal-body。然后，像在其他任何地方一样使用普通的网格系统类。

<div class="modal-body">
  <div class="container-fluid">
    <div class="row">
      <div class="col-md-4">.col-md-4</div>
      <div class="col-md-4 ml-auto">.col-md-4 .ml-auto</div>
    </div>
    <div class="row">
      <div class="col-md-3 ml-auto">.col-md-3 .ml-auto</div>
      <div class="col-md-2 ml-auto">.col-md-2 .ml-auto</div>
    </div>
    <div class="row">
      <div class="col-md-6 ml-auto">.col-md-6 .ml-auto</div>
    </div>
    <div class="row">
      <div class="col-sm-9">
        Level 1: .col-sm-9
        <div class="row">
          <div class="col-8 col-sm-6">
            Level 2: .col-8 .col-sm-6
          </div>
          <div class="col-4 col-sm-6">
            Level 2: .col-4 .col-sm-6
          </div>
        </div>
      </div>
    </div>
  </div>
</div>

各种模态内容

是否有一堆按钮都以相同的内容触发相同的模式？使用event.relatedTarget和HTML data-*属性（可能通过jQuery）根据所单击的按钮来更改模式的内容。

<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal" data-whatever="@mdo">Open modal for @mdo</button>
<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal" data-whatever="@fat">Open modal for @fat</button>
<button type="button" class="btn btn-primary" data-toggle="modal" data-target="#exampleModal" data-whatever="@getbootstrap">Open modal for @getbootstrap</button>

<div class="modal fade" id="exampleModal" tabindex="-1" aria-labelledby="exampleModalLabel" aria-hidden="true">
  <div class="modal-dialog">
    <div class="modal-content">
      <div class="modal-header">
        <h5 class="modal-title" id="exampleModalLabel">New message</h5>
        <button type="button" class="close" data-dismiss="modal" aria-label="Close">
          <span aria-hidden="true">&times;</span>
        </button>
      </div>
      <div class="modal-body">
        <form>
          <div class="form-group">
            <label for="recipient-name" class="col-form-label">Recipient:</label>
            <input type="text" class="form-control" id="recipient-name">
          </div>
          <div class="form-group">
            <label for="message-text" class="col-form-label">Message:</label>
            <textarea class="form-control" id="message-text"></textarea>
          </div>
        </form>
      </div>
      <div class="modal-footer">
        <button type="button" class="btn btn-secondary" data-dismiss="modal">Close</button>
        <button type="button" class="btn btn-primary">Send message</button>
      </div>
    </div>
  </div>
</div>

$('#exampleModal').on('show.bs.modal', function (event) {
  var button = $(event.relatedTarget) // Button that triggered the modal
  var recipient = button.data('whatever') // Extract info from data-* attributes
  // If necessary, you could initiate an AJAX request here (and then do the updating in a callback).
  // Update the modal's content. We'll use jQuery here, but you could use a data binding library or other methods instead.
  var modal = $(this)
  modal.find('.modal-title').text('New message to ' + recipient)
  modal.find('.modal-body input').val(recipient)
})

• 变更动画
  该$modal-fade-transform变量确定.modal-dialog模态淡入动画之前的变换状态，该$modal-show-transform变量确定.modal-dialog模态淡入动画结束时的变换。
  例如，如果要放大动画，可以设置$modal-fade-transform: scale(.8)。

• 删除动画
  对于仅显示而不是淡入显示的模态，请.fade从模态标记中删除该类。

<div class="modal" tabindex="-1" aria-labelledby="..." aria-hidden="true">
  ...
</div>

可选尺寸

模态具有三种可选尺寸，可通过放置在上的修饰符类获得.modal-dialog。这些大小会在某些断点处插入，以避免在较窄的视口上出现水平滚动条。

<div class="modal-dialog modal-xl">...</div>
<div class="modal-dialog modal-lg">...</div>
<div class="modal-dialog modal-sm">...</div>

方法

• .modal(options)
  将您的内容激活为模式。接受可选选项object。

$('#myModal').modal({
  keyboard: false
})

• .modal('toggle')
  手动切换模态。在实际显示或隐藏模式之前（即在shown.bs.modalor hidden.bs.modal事件发生之前）返回调用方。

$('#myModal').modal('toggle')

• .modal('show')
  手动打开模式。在实际显示模式之前（即shown.bs.modal事件发生之前）返回调用方。

$('#myModal').modal('show')

• .modal('hide')
  手动隐藏模式。在实际隐藏模式之前（即hidden.bs.modal事件发生之前）返回调用方。

$('#myModal').modal('hide')

• .modal('handleUpdate')
  如果模态的高度在打开时发生变化，则手动重新调整模态的位置（即，如果出现滚动条）。

$('#myModal').modal('handleUpdate')

• .modal('dispose')
  销毁元素的模态。

导航

基础导航
Bootstrap中可用的导航共享从基.nav类到活动和禁用状态的常规标记和样式。交换修饰符类可在每种样式之间切换。

<ul class="nav">
  <li class="nav-item">
    <a class="nav-link active" href="#">Active</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" href="#">Link</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" href="#">Link</a>
  </li>
  <li class="nav-item">
    <a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
  </li>
</ul>



<nav class="nav">
  <a class="nav-link active" href="#">Active</a>
  <a class="nav-link" href="#">Link</a>
  <a class="nav-link" href="#">Link</a>
  <a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
</nav>

水平对齐

使用flexbox实用程序更改导航的水平对齐方式。默认情况下，导航是左对齐的，但是您可以轻松地将它们更改为居中或右对齐。

• 居中.justify-content-center：

<ul class="nav justify-content-center">
  <li class="nav-item">
    <a class="nav-link active" href="#">Active</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" href="#">Link</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" href="#">Link</a>
  </li>
  <li class="nav-item">
    <a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
  </li>
</ul>

• 右对齐.justify-content-end：

<ul class="nav justify-content-end">
  <li class="nav-item">
    <a class="nav-link active" href="#">Active</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" href="#">Link</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" href="#">Link</a>
  </li>
  <li class="nav-item">
    <a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
  </li>
</ul>

垂直

通过使用.flex-column实用程序更改弹性项目方向来堆叠导航。

<ul class="nav flex-column">
  <li class="nav-item">
    <a class="nav-link active" href="#">Active</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" href="#">Link</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" href="#">Link</a>
  </li>
  <li class="nav-item">
    <a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
  </li>
</ul>

与往常一样，也可以不使用<ul>进行垂直导航。

<nav class="nav flex-column">
  <a class="nav-link active" href="#">Active</a>
  <a class="nav-link" href="#">Link</a>
  <a class="nav-link" href="#">Link</a>
  <a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
</nav>

标签

从上面获取基本导航，并添加.nav-tabs类以生成选项卡式界面。使用它们通过我们的标签JavaScript插件创建可标签区域。

<ul class="nav nav-tabs">
  <li class="nav-item">
    <a class="nav-link active" href="#">Active</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" href="#">Link</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" href="#">Link</a>
  </li>
  <li class="nav-item">
    <a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
  </li>
</ul>

胶囊
使用相同的HTML，.nav-tabs改为.nav-pills使用：

<ul class="nav nav-pills">
  <li class="nav-item">
    <a class="nav-link active" href="#">Active</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" href="#">Link</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" href="#">Link</a>
  </li>
  <li class="nav-item">
    <a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
  </li>
</ul>

填写并证明

强制您.nav的内容扩展两个修饰符类之一的全部可用宽度。要用.nav-items按比例填充所有可用空间，请使用.nav-fill。请注意，所有水平空间都被占用，但并非每个导航项都具有相同的宽度。

<ul class="nav nav-pills nav-fill">
  <li class="nav-item">
    <a class="nav-link active" href="#">Active</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" href="#">Much longer nav link</a>
  </li>
  <li class="nav-item">
    <a class="nav-link" href="#">Link</a>
  </li>
  <li class="nav-item">
    <a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
  </li>
</ul>

使用<nav>基于导航的导航时，可以安全地省略.nav-item，仅对.nav-link样式<a>元素进行必要。

<nav class="nav nav-pills nav-fill">
  <a class="nav-link active" href="#">Active</a>
  <a class="nav-link" href="#">Much longer nav link</a>
  <a class="nav-link" href="#">Link</a>
  <a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
</nav>

使用下拉菜单

添加带有一些额外HTML和下拉JavaScript插件的下拉菜单。

<ul class="nav nav-tabs">
  <li class="nav-item">
    <a class="nav-link active" href="#">Active</a>
  </li>
  <li class="nav-item dropdown">
    <a class="nav-link dropdown-toggle" data-toggle="dropdown" href="#" role="button" aria-haspopup="true" aria-expanded="false">Dropdown</a>
    <div class="dropdown-menu">
      <a class="dropdown-item" href="#">Action</a>
      <a class="dropdown-item" href="#">Another action</a>
      <a class="dropdown-item" href="#">Something else here</a>
      <div class="dropdown-divider"></div>
      <a class="dropdown-item" href="#">Separated link</a>
    </div>
  </li>
  <li class="nav-item">
    <a class="nav-link" href="#">Link</a>
  </li>
  <li class="nav-item">
    <a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
  </li>
</ul>

//胶囊下拉菜单
<ul class="nav nav-pills">
  <li class="nav-item">
    <a class="nav-link active" href="#">Active</a>
  </li>
  <li class="nav-item dropdown">
    <a class="nav-link dropdown-toggle" data-toggle="dropdown" href="#" role="button" aria-haspopup="true" aria-expanded="false">Dropdown</a>
    <div class="dropdown-menu">
      <a class="dropdown-item" href="#">Action</a>
      <a class="dropdown-item" href="#">Another action</a>
      <a class="dropdown-item" href="#">Something else here</a>
      <div class="dropdown-divider"></div>
      <a class="dropdown-item" href="#">Separated link</a>
    </div>
  </li>
  <li class="nav-item">
    <a class="nav-link" href="#">Link</a>
  </li>
  <li class="nav-item">
    <a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
  </li>
</ul>

<ul class="nav nav-tabs" id="myTab" role="tablist">
  <li class="nav-item" role="presentation">
    <a class="nav-link active" id="home-tab" data-toggle="tab" href="#home" role="tab" aria-controls="home" aria-selected="true">Home</a>
  </li>
  <li class="nav-item" role="presentation">
    <a class="nav-link" id="profile-tab" data-toggle="tab" href="#profile" role="tab" aria-controls="profile" aria-selected="false">Profile</a>
  </li>
  <li class="nav-item" role="presentation">
    <a class="nav-link" id="contact-tab" data-toggle="tab" href="#contact" role="tab" aria-controls="contact" aria-selected="false">Contact</a>
  </li>
</ul>
<div class="tab-content" id="myTabContent">
  <div class="tab-pane fade show active" id="home" role="tabpanel" aria-labelledby="home-tab">...</div>
  <div class="tab-pane fade" id="profile" role="tabpanel" aria-labelledby="profile-tab">...</div>
  <div class="tab-pane fade" id="contact" role="tabpanel" aria-labelledby="contact-tab">...</div>
</div>

<nav>
  <div class="nav nav-tabs" id="nav-tab" role="tablist">
    <a class="nav-link active" id="nav-home-tab" data-toggle="tab" href="#nav-home" role="tab" aria-controls="nav-home" aria-selected="true">Home</a>
    <a class="nav-link" id="nav-profile-tab" data-toggle="tab" href="#nav-profile" role="tab" aria-controls="nav-profile" aria-selected="false">Profile</a>
    <a class="nav-link" id="nav-contact-tab" data-toggle="tab" href="#nav-contact" role="tab" aria-controls="nav-contact" aria-selected="false">Contact</a>
  </div>
</nav>
<div class="tab-content" id="nav-tabContent">
  <div class="tab-pane fade show active" id="nav-home" role="tabpanel" aria-labelledby="nav-home-tab">...</div>
  <div class="tab-pane fade" id="nav-profile" role="tabpanel" aria-labelledby="nav-profile-tab">...</div>
  <div class="tab-pane fade" id="nav-contact" role="tabpanel" aria-labelledby="nav-contact-tab">...</div>
</div>

<ul class="nav nav-pills mb-3" id="pills-tab" role="tablist">
  <li class="nav-item" role="presentation">
    <a class="nav-link active" id="pills-home-tab" data-toggle="pill" href="#pills-home" role="tab" aria-controls="pills-home" aria-selected="true">Home</a>
  </li>
  <li class="nav-item" role="presentation">
    <a class="nav-link" id="pills-profile-tab" data-toggle="pill" href="#pills-profile" role="tab" aria-controls="pills-profile" aria-selected="false">Profile</a>
  </li>
  <li class="nav-item" role="presentation">
    <a class="nav-link" id="pills-contact-tab" data-toggle="pill" href="#pills-contact" role="tab" aria-controls="pills-contact" aria-selected="false">Contact</a>
  </li>
</ul>
<div class="tab-content" id="pills-tabContent">
  <div class="tab-pane fade show active" id="pills-home" role="tabpanel" aria-labelledby="pills-home-tab">...</div>
  <div class="tab-pane fade" id="pills-profile" role="tabpanel" aria-labelledby="pills-profile-tab">...</div>
  <div class="tab-pane fade" id="pills-contact" role="tabpanel" aria-labelledby="pills-contact-tab">...</div>
</div>

<div class="row">
  <div class="col-3">
    <div class="nav flex-column nav-pills" id="v-pills-tab" role="tablist" aria-orientation="vertical">
      <a class="nav-link active" id="v-pills-home-tab" data-toggle="pill" href="#v-pills-home" role="tab" aria-controls="v-pills-home" aria-selected="true">Home</a>
      <a class="nav-link" id="v-pills-profile-tab" data-toggle="pill" href="#v-pills-profile" role="tab" aria-controls="v-pills-profile" aria-selected="false">Profile</a>
      <a class="nav-link" id="v-pills-messages-tab" data-toggle="pill" href="#v-pills-messages" role="tab" aria-controls="v-pills-messages" aria-selected="false">Messages</a>
      <a class="nav-link" id="v-pills-settings-tab" data-toggle="pill" href="#v-pills-settings" role="tab" aria-controls="v-pills-settings" aria-selected="false">Settings</a>
    </div>
  </div>
  <div class="col-9">
    <div class="tab-content" id="v-pills-tabContent">
      <div class="tab-pane fade show active" id="v-pills-home" role="tabpanel" aria-labelledby="v-pills-home-tab">...</div>
      <div class="tab-pane fade" id="v-pills-profile" role="tabpanel" aria-labelledby="v-pills-profile-tab">...</div>
      <div class="tab-pane fade" id="v-pills-messages" role="tabpanel" aria-labelledby="v-pills-messages-tab">...</div>
      <div class="tab-pane fade" id="v-pills-settings" role="tabpanel" aria-labelledby="v-pills-settings-tab">...</div>
    </div>
  </div>
</div>

导航栏

Bootstrap强大的响应式导航标题导航栏的文档和示例。包括对品牌，导航等的支持，包括对我们的合拢插件的支持。

了解：

• 导航栏需要包装.navbar以.navbar-expand{-sm|-md|-lg|-xl}用于响应式折叠和配色方案类。
• 导航栏及其内容默认情况下是流畅的。使用可选容器限制其水平宽度。
• 使用我们的间隔和柔性的实用工具类，用于控制导航栏内间隔和对齐。
• 导航栏默认情况下是响应式的，但是您可以轻松地对其进行修改以进行更改。
• 打印时，导航栏默认为隐藏。迫使他们通过添加打印.d-print到.navbar。
• 通过使用<nav>元素来确保可访问性，或者如果使用更通用的元素（例如使用）来确保可访问性，则在每个导航栏上<div>添加一个，role="navigation"以将其明确标识为辅助技术用户的界标区域。

支持内容:

Navbars内置了对少数子组件的支持。根据需要从以下选项中进行选择：

• .navbar-brand 您公司，产品或项目的名称。
• .navbar-nav 全高和轻量级导航（包括对下拉菜单的支持）。
• .navbar-toggler与我们的崩溃插件和其他导航切换行为配合使用。
• .form-inline用于任何形式的控件和动作。
• .navbar-text用于添加垂直居中的文本字符串。
  -.collapse.navbar-collapse 用于通过父断点分组和隐藏导航栏内容。

响应式轻型导航栏中包含的所有子组件的示例，该导航栏在lg（大）断点处自动折叠:

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <a class="navbar-brand" href="#">Navbar</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>

  <div class="collapse navbar-collapse" id="navbarSupportedContent">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Link</a>
      </li>
      <li class="nav-item dropdown">
        <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
          Dropdown
        </a>
        <div class="dropdown-menu" aria-labelledby="navbarDropdown">
          <a class="dropdown-item" href="#">Action</a>
          <a class="dropdown-item" href="#">Another action</a>
          <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="#">Something else here</a>
        </div>
      </li>
      <li class="nav-item">
        <a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
      </li>
    </ul>
    <form class="form-inline my-2 my-lg-0">
      <input class="form-control mr-sm-2" type="search" placeholder="Search" aria-label="Search">
      <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
    </form>
  </div>
</nav>

品牌

该.navbar-brand可应用于大部分元素，但是锚效果最好的一些元素可能需要的工具类或自定义样式。

<!-- As a link -->
<nav class="navbar navbar-light bg-light">
  <a class="navbar-brand" href="#">Navbar</a>
</nav>

<!-- As a heading -->
<nav class="navbar navbar-light bg-light">
  <span class="navbar-brand mb-0 h1">Navbar</span>
</nav>

<!-- Just an image -->
<nav class="navbar navbar-light bg-light">
  <a class="navbar-brand" href="#">
    <img src="/docs/4.5/assets/brand/bootstrap-solid.svg" width="30" height="30" alt="" loading="lazy">
  </a>
</nav>

<!-- Image and text -->
<nav class="navbar navbar-light bg-light">
  <a class="navbar-brand" href="#">
    <img src="/docs/4.5/assets/brand/bootstrap-solid.svg" width="30" height="30" class="d-inline-block align-top" alt="" loading="lazy">
    Bootstrap
  </a>
</nav>

导航

Navbar导航链接以.nav自己的选项为基础，带有自己的修改器类，并且需要使用切换器类来进行适当的响应式样式。

活动状态-带有.active-表示当前页面可以直接应用于.nav-links或它们的直接父级.nav-items。

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <a class="navbar-brand" href="#">Navbar</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <div class="collapse navbar-collapse" id="navbarNav">
    <ul class="navbar-nav">
      <li class="nav-item active">
        <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Features</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Pricing</a>
      </li>
      <li class="nav-item">
        <a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
      </li>
    </ul>
  </div>
</nav>

可以根据需要完全避免基于列表的方法:

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <a class="navbar-brand" href="#">Navbar</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNavAltMarkup" aria-controls="navbarNavAltMarkup" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <div class="collapse navbar-collapse" id="navbarNavAltMarkup">
    <div class="navbar-nav">
      <a class="nav-link active" href="#">Home <span class="sr-only">(current)</span></a>
      <a class="nav-link" href="#">Features</a>
      <a class="nav-link" href="#">Pricing</a>
      <a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
    </div>
  </div>
</nav>

嵌套下拉菜单

可以在导航栏导航中使用下拉菜单。下拉菜单需要用于定位的缠绕元件，所以一定要使用单独的和嵌套的元素.nav-item和.nav-link，如下所示。

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <a class="navbar-brand" href="#">Navbar</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNavDropdown" aria-controls="navbarNavDropdown" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <div class="collapse navbar-collapse" id="navbarNavDropdown">
    <ul class="navbar-nav">
      <li class="nav-item active">
        <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Features</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Pricing</a>
      </li>
      <li class="nav-item dropdown">
        <a class="nav-link dropdown-toggle" href="#" id="navbarDropdownMenuLink" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
          Dropdown link
        </a>
        <div class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
          <a class="dropdown-item" href="#">Action</a>
          <a class="dropdown-item" href="#">Another action</a>
          <a class="dropdown-item" href="#">Something else here</a>
        </div>
      </li>
    </ul>
  </div>
</nav>

表单

使用将各种表单控件和组件放置在导航栏中.form-inline。

<nav class="navbar navbar-light bg-light">
  <form class="form-inline">
    <input class="form-control mr-sm-2" type="search" placeholder="Search" aria-label="Search">
    <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
  </form>
</nav>

直接子元素在.navbar使用flex布局，并且默认为justify-content: space-between。根据需要使用其他Flex实用程序来调整此行为。

<nav class="navbar navbar-light bg-light">
  <a class="navbar-brand">Navbar</a>
  <form class="form-inline">
    <input class="form-control mr-sm-2" type="search" placeholder="Search" aria-label="Search">
    <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
  </form>
</nav>

输入组

<nav class="navbar navbar-light bg-light">
  <form class="form-inline">
    <div class="input-group">
      <div class="input-group-prepend">
        <span class="input-group-text" id="basic-addon1">@</span>
      </div>
      <input type="text" class="form-control" placeholder="Username" aria-label="Username" aria-describedby="basic-addon1">
    </div>
  </form>
</nav>

这些导航栏形式也支持各种按钮。这也非常提醒我们可以使用垂直对齐工具来对齐不同大小的元素。

<nav class="navbar navbar-light bg-light">
  <form class="form-inline">
    <button class="btn btn-outline-success" type="button">Main button</button>
    <button class="btn btn-sm btn-outline-secondary" type="button">Smaller button</button>
  </form>
</nav>

文本

导航栏可能在的帮助下包含一些文本.navbar-text。此类调整文本字符串的垂直对齐和水平间距。

<nav class="navbar navbar-light bg-light">
  <span class="navbar-text">
    带有内联元素的导航栏文本
  </span>
</nav>

根据需要与其他组件和实用程序混合并匹配:

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <a class="navbar-brand" href="#">Navbar w/ text</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarText" aria-controls="navbarText" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <div class="collapse navbar-collapse" id="navbarText">
    <ul class="navbar-nav mr-auto">
      <li class="nav-item active">
        <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Features</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Pricing</a>
      </li>
    </ul>
    <span class="navbar-text">
      Navbar text with an inline element
    </span>
  </div>
</nav>

导航背景颜色

配色方案
选择.navbar-light``用于浅色背景颜色或.navbar-dark深色背景颜色。然后，使用.bg-*实用程序进行自定义。

<nav class="navbar navbar-dark bg-dark">
  <!-- Navbar content -->
</nav>

<nav class="navbar navbar-dark bg-primary">
  <!-- Navbar content -->
</nav>

<nav class="navbar navbar-light" style="background-color: #e3f2fd;">
  <!-- Navbar content -->
</nav>

导航栏布局

可以将导航栏包裹在.container中间，以使其在页面上居中，也可以在其中添加一个导航栏，仅将固定或静态顶部导航栏的内容居中。

<div class="container">
  <nav class="navbar navbar-expand-lg navbar-light bg-light">
    <a class="navbar-brand" href="#">Navbar</a>
  </nav>
</div>

当容器在导航栏中时，在低于指定.navbar-expand{-sm|-md|-lg|-xl}类的断点处删除其水平填充。这样可以确保在导航栏合拢时，我们不会在不必要的情况下在较低视口上加倍填充。

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <div class="container">
    <a class="navbar-brand" href="#">Navbar</a>
  </div>
</nav>

位置

从固定到顶部，固定到底部或固定在顶部进行选择（滚动页面直到到达顶部，然后停留在顶部）。固定的导航栏使用position:fixed，这意味着它们是从DOM的正常流程中拉出的，并且可能需要自定义CSS（例如padding-top在上<body>），以防止与其他元素重叠。

另请注意.sticky-top用途position: sticky，并非所有浏览器都完全支持。
默认:

<nav class="navbar navbar-light bg-light">
  <a class="navbar-brand" href="#">Default</a>
</nav>

固定在顶部:

<nav class="navbar fixed-top navbar-light bg-light">
  <a class="navbar-brand" href="#">Fixed top</a>
</nav>

固定在底部:

<nav class="navbar fixed-bottom navbar-light bg-light">
  <a class="navbar-brand" href="#">Fixed bottom</a>
</nav>

粘在顶部:

<nav class="navbar sticky-top navbar-light bg-light">
  <a class="navbar-brand" href="#">Sticky top</a>
</nav>

响应

导航栏可以利用.navbar-toggler，.navbar-collapse和.navbar-expand{-sm|-md|-lg|-xl}类在内容折叠到按钮后时进行更改。与其他实用程序结合使用，您可以轻松选择何时显示或隐藏特定元素。

对于永不崩溃.navbar-expand的导航栏，请在导航栏上添加类。对于始终折叠的导航栏，请勿添加任何.navbar-expand类。

切换器

导航栏切换器默认情况下是左对齐的，但是如果它们跟随诸如的兄弟元素.navbar-brand，它们将自动对齐到最右端。反转标记将反转切换器的位置。以下是不同切换样式的示例。

.navbar-brand最低断点处没有显示：

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarTogglerDemo01" aria-controls="navbarTogglerDemo01" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <div class="collapse navbar-collapse" id="navbarTogglerDemo01">
    <a class="navbar-brand" href="#">Hidden brand</a>
    <ul class="navbar-nav mr-auto mt-2 mt-lg-0">
      <li class="nav-item active">
        <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Link</a>
      </li>
      <li class="nav-item">
        <a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
      </li>
    </ul>
    <form class="form-inline my-2 my-lg-0">
      <input class="form-control mr-sm-2" type="search" placeholder="Search" aria-label="Search">
      <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
    </form>
  </div>
</nav>

左侧显示品牌名称，右侧显示切换器：

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <a class="navbar-brand" href="#">Navbar</a>
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarTogglerDemo02" aria-controls="navbarTogglerDemo02" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>

  <div class="collapse navbar-collapse" id="navbarTogglerDemo02">
    <ul class="navbar-nav mr-auto mt-2 mt-lg-0">
      <li class="nav-item active">
        <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Link</a>
      </li>
      <li class="nav-item">
        <a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
      </li>
    </ul>
    <form class="form-inline my-2 my-lg-0">
      <input class="form-control mr-sm-2" type="search" placeholder="Search">
      <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
    </form>
  </div>
</nav>

左侧带有切换开关，右侧带有品牌名称：

<nav class="navbar navbar-expand-lg navbar-light bg-light">
  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarTogglerDemo03" aria-controls="navbarTogglerDemo03" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
  </button>
  <a class="navbar-brand" href="#">Navbar</a>

  <div class="collapse navbar-collapse" id="navbarTogglerDemo03">
    <ul class="navbar-nav mr-auto mt-2 mt-lg-0">
      <li class="nav-item active">
        <a class="nav-link" href="#">Home <span class="sr-only">(current)</span></a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Link</a>
      </li>
      <li class="nav-item">
        <a class="nav-link disabled" href="#" tabindex="-1" aria-disabled="true">Disabled</a>
      </li>
    </ul>
    <form class="form-inline my-2 my-lg-0">
      <input class="form-control mr-sm-2" type="search" placeholder="Search" aria-label="Search">
      <button class="btn btn-outline-success my-2 my-sm-0" type="submit">Search</button>
    </form>
  </div>
</nav>

折叠内容

有时，您想使用折叠插件来触发页面其他位置的隐藏内容。由于我们的插件适用于id和data-target，因此很容易做到！

<div class="fixed-top">
  <div class="collapse" id="navbarToggleExternalContent">
    <div class="bg-dark p-4">
      <h5 class="text-white h4">Collapsed content</h5>
      <span class="text-muted">Toggleable via the navbar brand.</span>
    </div>
  </div>
  <nav class="navbar navbar-dark bg-dark">
    <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarToggleExternalContent" aria-controls="navbarToggleExternalContent" aria-expanded="false" aria-label="Toggle navigation">
      <span class="navbar-toggler-icon"></span>
    </button>
  </nav>
</div>

分页

用于显示分页以指示一系列相关内容的文档和示例跨越多个页面存在。
网页可能有不止一个这样的导航部分，它的最好提供一个描述性aria-label的<nav>，以反映其目的。例如，如果使用分页组件在一组搜索结果之间导航，则适当的标签可以为aria-label="Search results pages"。

<nav aria-label="Page navigation example">
  <ul class="pagination">
    <li class="page-item"><a class="page-link" href="#">Previous</a></li>
    <li class="page-item"><a class="page-link" href="#">1</a></li>
    <li class="page-item"><a class="page-link" href="#">2</a></li>
    <li class="page-item"><a class="page-link" href="#">3</a></li>
    <li class="page-item"><a class="page-link" href="#">Next</a></li>
  </ul>
</nav>

使用图标

通过aria属性在某些分页链接中使用图标或符号代替文本

<nav aria-label="Page navigation example">
  <ul class="pagination">
    <li class="page-item">
      <a class="page-link" href="#" aria-label="Previous">
        <span aria-hidden="true">&laquo;</span>
      </a>
    </li>
    <li class="page-item"><a class="page-link" href="#">1</a></li>
    <li class="page-item"><a class="page-link" href="#">2</a></li>
    <li class="page-item"><a class="page-link" href="#">3</a></li>
    <li class="page-item">
      <a class="page-link" href="#" aria-label="Next">
        <span aria-hidden="true">&raquo;</span>
      </a>
    </li>
  </ul>
</nav>

禁用和活动状态
分页链接可针对不同情况进行自定义。使用.disabled该出现非可点击和链接.active来表示当前页面。

<nav aria-label="...">
  <ul class="pagination">
    <li class="page-item disabled">
      <a class="page-link" href="#" tabindex="-1" aria-disabled="true">Previous</a>
    </li>
    <li class="page-item"><a class="page-link" href="#">1</a></li>
    <li class="page-item active" aria-current="page">
      <a class="page-link" href="#">2 <span class="sr-only">(current)</span></a>
    </li>
    <li class="page-item"><a class="page-link" href="#">3</a></li>
    <li class="page-item">
      <a class="page-link" href="#">Next</a>
    </li>
  </ul>
</nav>

可以选择将活动锚或禁用锚替换为<span>，或者在上一个/下一个箭头的情况下忽略该锚，以删除单击功能并在保留预期样式的同时防止键盘聚焦。

<nav aria-label="...">
  <ul class="pagination">
    <li class="page-item disabled">
      <span class="page-link">Previous</span>
    </li>
    <li class="page-item"><a class="page-link" href="#">1</a></li>
    <li class="page-item active" aria-current="page">
      <span class="page-link">
        2
        <span class="sr-only">(current)</span>
      </span>
    </li>
    <li class="page-item"><a class="page-link" href="#">3</a></li>
    <li class="page-item">
      <a class="page-link" href="#">Next</a>
    </li>
  </ul>
</nav>

大小

添加.pagination-lg或.pagination-sm增加尺寸

<nav aria-label="...">
  <ul class="pagination pagination-lg">
    <li class="page-item active" aria-current="page">
      <span class="page-link">
        1
        <span class="sr-only">(current)</span>
      </span>
    </li>
    <li class="page-item"><a class="page-link" href="#">2</a></li>
    <li class="page-item"><a class="page-link" href="#">3</a></li>
  </ul>
</nav>

<nav aria-label="...">
  <ul class="pagination pagination-sm">
    <li class="page-item active" aria-current="page">
      <span class="page-link">
        1
        <span class="sr-only">(current)</span>
      </span>
    </li>
    <li class="page-item"><a class="page-link" href="#">2</a></li>
    <li class="page-item"><a class="page-link" href="#">3</a></li>
  </ul>
</nav>

对齐方式

使用flexbox实用程序更改分页组件的对齐方式。
居中对齐:

<nav aria-label="Page navigation example">
  <ul class="pagination justify-content-center">
    <li class="page-item disabled">
      <a class="page-link" href="#" tabindex="-1" aria-disabled="true">Previous</a>
    </li>
    <li class="page-item"><a class="page-link" href="#">1</a></li>
    <li class="page-item"><a class="page-link" href="#">2</a></li>
    <li class="page-item"><a class="page-link" href="#">3</a></li>
    <li class="page-item">
      <a class="page-link" href="#">Next</a>
    </li>
  </ul>
</nav>

右对齐:

<nav aria-label="Page navigation example">
  <ul class="pagination justify-content-end">
    <li class="page-item disabled">
      <a class="page-link" href="#" tabindex="-1" aria-disabled="true">Previous</a>
    </li>
    <li class="page-item"><a class="page-link" href="#">1</a></li>
    <li class="page-item"><a class="page-link" href="#">2</a></li>
    <li class="page-item"><a class="page-link" href="#">3</a></li>
    <li class="page-item">
      <a class="page-link" href="#">Next</a>
    </li>
  </ul>
</nav>

滚动式

根据滚动位置自动更新Bootstrap导航或列表组组件，以指示当前在视口中处于活动状态的链接。

Scrollspy了解

Scrollspy有一些要求才能正常运行：

• 如果您要从源代码构建JavaScript，则需要使用util.js。
• 必须在Bootstrap 导航组件或列表组上使用它。
• Scrollspy需要position: relative;您正在监视的元素，通常是<body>。
• 侦查除以外的其他元素时<body>，请务必进行height设置并overflow-y: scroll;套用。
• 锚点（<a>）是必需的，并且必须指向带有该元素的元素id。

成功实施后，您的导航或列表组将进行相应的更新，并.active根据其相关目标将类从一项移至下一项。

导航栏中的示例

<nav id="navbar-example2" class="navbar navbar-light bg-light">
  <a class="navbar-brand" href="#">Navbar</a>
  <ul class="nav nav-pills">
    <li class="nav-item">
      <a class="nav-link" href="#fat">@fat</a>
    </li>
    <li class="nav-item">
      <a class="nav-link" href="#mdo">@mdo</a>
    </li>
    <li class="nav-item dropdown">
      <a class="nav-link dropdown-toggle" data-toggle="dropdown" href="#" role="button" aria-haspopup="true" aria-expanded="false">Dropdown</a>
      <div class="dropdown-menu">
        <a class="dropdown-item" href="#one">one</a>
        <a class="dropdown-item" href="#two">two</a>
        <div role="separator" class="dropdown-divider"></div>
        <a class="dropdown-item" href="#three">three</a>
      </div>
    </li>
  </ul>
</nav>
<div data-spy="scroll" data-target="#navbar-example2" data-offset="0">
  <h4 id="fat">@fat</h4>
  <p>...</p>
  <h4 id="mdo">@mdo</h4>
  <p>...</p>
  <h4 id="one">one</h4>
  <p>...</p>
  <h4 id="two">two</h4>
  <p>...</p>
  <h4 id="three">three</h4>
  <p>...</p>
</div>

嵌套导航

Scrollspy也适用于嵌套.navs。如果是嵌套.nav的.active，它的父母也会嵌套.active。滚动导航栏旁边的区域，然后查看活动的区域更改。

<nav id="navbar-example3" class="navbar navbar-light bg-light">
  <a class="navbar-brand" href="#">Navbar</a>
  <nav class="nav nav-pills flex-column">
    <a class="nav-link" href="#item-1">Item 1</a>
    <nav class="nav nav-pills flex-column">
      <a class="nav-link ml-3 my-1" href="#item-1-1">Item 1-1</a>
      <a class="nav-link ml-3 my-1" href="#item-1-2">Item 1-2</a>
    </nav>
    <a class="nav-link" href="#item-2">Item 2</a>
    <a class="nav-link" href="#item-3">Item 3</a>
    <nav class="nav nav-pills flex-column">
      <a class="nav-link ml-3 my-1" href="#item-3-1">Item 3-1</a>
      <a class="nav-link ml-3 my-1" href="#item-3-2">Item 3-2</a>
    </nav>
  </nav>
</nav>

<div data-spy="scroll" data-target="#navbar-example3" data-offset="0">
  <h4 id="item-1">Item 1</h4>
  <p>...</p>
  <h5 id="item-1-1">Item 1-1</h5>
  <p>...</p>
  <h5 id="item-1-2">Item 1-2</h5>
  <p>...</p>
  <h4 id="item-2">Item 2</h4>
  <p>...</p>
  <h4 id="item-3">Item 3</h4>
  <p>...</p>
  <h5 id="item-3-1">Item 3-1</h5>
  <p>...</p>
  <h5 id="item-3-2">Item 3-2</h5>
  <p>...</p>
</div>

列表组

Scrollspy也适用于.list-groups。滚动列表组旁边的区域，并观察活动区域的变化。

<div id="list-example" class="list-group">
  <a class="list-group-item list-group-item-action" href="#list-item-1">Item 1</a>
  <a class="list-group-item list-group-item-action" href="#list-item-2">Item 2</a>
  <a class="list-group-item list-group-item-action" href="#list-item-3">Item 3</a>
  <a class="list-group-item list-group-item-action" href="#list-item-4">Item 4</a>
</div>
<div data-spy="scroll" data-target="#list-example" data-offset="0" class="scrollspy-example">
  <h4 id="list-item-1">Item 1</h4>
  <p>...</p>
  <h4 id="list-item-2">Item 2</h4>
  <p>...</p>
  <h4 id="list-item-3">Item 3</h4>
  <p>...</p>
  <h4 id="list-item-4">Item 4</h4>
  <p>...</p>
</div>

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四、Bootstrap4官方文档 | v4核心 – 组件(二)