main idea

Data driven: page views and data binding two-way binding, do not manipulate dom, view and change the data at the same time
Components of: business function is a separate module detached

MVVM

View: DOM, view
ViewModel: view and way binding model
Model: js native objects

Vue basic grammar

Creating Vue examples

Direct introduction of the <head> <script> After downloading

<head>
    <meta charset="UTF-8">
    <title>Vue 入门</title>
    <script src="./vue.js"></script>
</head>

Reference CDN:

<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/vue.js"></script>

Mount point, templates and examples

Mount Point: Refers to the Pages tab, mount Vue

Contents of mount points: Templates

Example: JavaScript in new Vue () instance object

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Vue 入门</title>
    <script src="./vue.js"></script>
</head>
<body>
<!--挂载点、模板、实例之间的关系
div为挂载点，通过ID绑定
模板可以写到挂载点内部和实例中-->
<div id="root">{{msg}}
    <!--挂载点内部的内容为模板-->
    <p>这里是挂载点内部的模板{{temMsg}}</p>
</div>
<script>
    // vue实例
    new Vue({
        //指定实例的挂载点，Vue去接管哪个元素内容，绑定DOM节点
        el: "#root",
        // 模板也可以写到实例中,但是这样挂载点中的内容就不会被显示
        template:'<i>这里是实例中的模板{{temMsg}}</i>',
        // 数据内容
        data: {
            msg: "hello world",
            temMsg:"template"
        }
    });
</script>
</body>
</html>

Examples of data Vue

Data Object: data

Page reference data instances:

{{}}、v-text、v-html

<body>
<div id="root">
    <!--{{}}为插值表达式语法
    v-text:Vue中的指令，只能输出文本，会转义
    v-html:Vue中的指令,可以输出标签，不会转义
    -->
    <ul>
        <li>{{msg}}</li>
        <li v-text="vText"></li>
        <li v-html="vHtml"></li>
        <li v-text="content"></li>
        <li v-html="content"></li>
    </ul>
</div>
<script>
    // vue实例
    new Vue({
        el: "#root",
        data: {
            msg: "{{}}双括号插值表达式",
            vText: "v-text是Vue指令",
            vHtml:"v-html是Vue指令",
            content:"<i>测试v-text和v-html之间的不同</i>"
        }
    });
</script>
</body>

Vue events and methods

Binding elements to the event v-on: can also be abbreviated as @

Function object: methods

Vue features: data-oriented programming, no need to operate the DOM, data change, page change

<body>
<div id="root">
    <!--
    v-on:Vue绑定事件,
    改变挂载点中的内容不要操作DOM，应该修改实例中的数据
    -->
    <ul>
        <li v-on:click="()=>{alert('绑定了点击事件 v-on:click')}">{{msg}}:箭头函数有问题</li>
        <li v-on:click="handleClick">{{msg}}:引用实例中methods对象下的方法</li>
        <li @click="changeData">{{changeMsg}}</li>
    </ul>
</div>
<script>
    // vue实例
    new Vue({
        el: "#root",
        data: {
            msg: "v-on:click   点击事件",
            changeMsg: "点击改变内容"
        },
        methods: {
            handleClick: function () {
                alert("绑定了点击事件 v-on:click")
            },
            changeData: function () {
                // this指向data 修改数据
                this.changeMsg="内容被改变";
            }
        }
    })
    ;
</script>
</body>

Binding Properties

Binding properties of v-bind: title = 'variable name' can be written: title = 'variable name' command template
variable names Vue attribute data is a data object
behind is a = js expression number, may = 'input Character + title '

<div id="root">
    <ul>
        <li title="title 的名字">鼠标移动过来显示</li>
        <li v-bind:title="title">属性绑定</li>
        <!--  =号后边为js表达式  title 是变量-->
        <li :title="'这是一个'+ title">属性绑定</li>
    </ul>
</div>
<script>
    // vue实例
    new Vue({
        el: "#root",
        data: {
            title: "实例中的数据"
        }
    })
</script>

Two-way data binding

Way binding: the decision to display the data page, the page can not decide what data

Two-way binding: template directives v-model, data content pages and any change, another also changed

<div id="root">
    <ul>
        <li><input :value="content"/></li>
        <li><input v-model="content"/></li>
        <li>{{content}}</li>
    </ul>
</div>
<script>
    // vue实例
    new Vue({
        el: "#root",
        data: {
            content: "this is content!"
        }
    })
</script>

Calculated with the listener properties

Object attributes computed from other attributes calculated from,

Other uses dependency property does not change the cached value is not recalculated

watch: listener object; monitor data changes, the data is changed trigger

<div id="root">
    <ul>
        <li>姓：<input v-model="firstName"/></li>
        <li>名：<input v-model="lastName"/></li>
        <li>{{firstName}}{{lastName}}</li>
        <li>fullName 属性计算：{{fullName}}</li>
        <li>侦听姓名修改次数：{{count}}</li>
        <li>侦听fullName数据变化：{{fullCount}}</li>
    </ul>
</div>
<script>
    // vue实例
    new Vue({
        el: "#root",
        data: {
            firstName: "",
            lastName: "",
            count: 0,
            fullCount: 0
        },
        // 计算属性：由其它属性计算而来
        computed: {
            fullName: function () {
                return this.firstName + ' ' + this.lastName;
            }
        },
        // 侦听器：监听数据变化
        watch: {
            // 侦听数据属性
            firstName: function () {
                this.count++;
            },
            lastName: function () {
                this.count++;
            },
            // 侦听计算属性
            fullName: function () {
                return this.fullCount++;
            }
        }
    })
</script>

v-if、v-show、v-for指令

v-if: control the presence or absence of DOM, false delete DOM

v-show: DOM control display or not Hide label DOM

v-for: traversing the data, data display cycle, increase: key = 'item' to improve efficiency, but not the same as the key value

<div id="root">
    <ul>
        <li><p v-if="show">hello world</p></li>
        <li><p v-show="show">hello world</p></li>
        <li>
            <button @click="handleClick">toggle</button>
        </li>
    </ul>
    <ul>
        <li v-for="item of list">{{item}}</li>
    </ul>
    <ul>
        <li v-for="(item,index) of list" :key="index">{{item}}</li>
    </ul>
</div>
<script>
    // vue实例
    new Vue({
        el: "#root",
        data: {
            show: true,
            list: [1, 2, 3]
        },
        methods: {
            handleClick: function () {
                this.show = !this.show;
            }
        }
    })
</script>