JavaScript DOM three ways to create elements

Three ways to create elements:

document.write()
element.innerHTML
document.createElement()

1. `document.write()`

Implementation code:

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <button>btn</button>
    <p>段落</p>
    <div class="inner">inner</div>
    <div class="create">create</div>
    <script>
        var btn = document.querySelector('button');
        btn.onclick = function() {
     
     
            document.write('<div>123</div>');
        }
    </script>
</body>

</html>

Initial page:
Insert picture description here

Realization effect: After
clicking the "btn" button:
Insert picture description here
Obviously, using the document.write()create element, if the page document flow is loaded, calling the event will cause the page to be redrawn

2. `element.innerHTML`

(1) String splicing method:

Implementation code:

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <button>btn</button>
    <p>段落</p>
    <div class="inner">inner</div>
    <div class="create">create</div>
    <script>
        var inner = document.querySelector('.inner');
        inner.innerHTML += ' <a href="#">我是后来加的链接，字符串拼接方式</a>';
    </script>
</body>

</html>

Realization effect:
Insert picture description here

(2) How to add array elements:

Implementation code:

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <button>btn</button>
    <p>段落</p>
    <div class="inner">inner</div>
    <div class="create">create</div>
    <script>
        var inner = document.querySelector('.inner');
        // 创建空数组
        var arr = [];
        // 将需要添加的元素，添加到数组中
        arr.push('<a href="#"> 我是后来加的链接，数组方式</a>');
        // 将数组转化为字符串，再给到inner节点
        inner.innerHTML = arr.join('');
    </script>
</body>

</html>

Realization effect:
Insert picture description here

3. `document.createElement()`

Implementation code:

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <button>btn</button>
    <p>段落</p>
    <div class="inner">inner</div>
    <div class="create">create</div>
    <script>
        var create = document.querySelector('.create');
        var a = document.createElement('a');
        create.appendChild(a);
    </script>
</body>

</html>

Realization effect:
Insert picture description here

to sum up:

document.writeIt is a content stream that directly writes content to the page, but after the document stream is executed, it will cause the page to be redrawn .
innerHTMLIt is to write the content to a DOM node , which will not cause the page to be redrawn. Create multiple elements, the structure is slightly more complicated. It can be added in string splicing mode or array mode .
createElement()Create multiple elements to make the structure clearer.