<!DOCTYPE HTML>
<html lang="en-US">
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<button id='btn'>创建元素</button>
<script type="text/javascript">
var btn = document.getElementById('btn');
//注册点击事件
btn.onclick = function(){
//创建一个元素
var h1 = document.createElement('h1');
h1.innerHTML = "这是新增h1标签";
console.log( h1 );
//使用appendChild的方式
//document.body.appendChild( h1 );
//使用insertBefore的方式
//是在父元素中，先找一个节点，然后插入到它之前
document.body.insertBefore(h1,btn); //新插入的节点是h1，作为第一个参数
}
</script>
</body>
</html>
三叔2017-06-14 10:55:37
With quotes it is a string
var h1 = document.createElement('h1');
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A B
Unquoted are variables:
document.body.appendChild(h1);
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A
See the document: document.getElementById
element = document.getElementById(id);
element is an Element object. If the element with the specific ID does not exist in the current document, return null.
id is a case-sensitive string, which represents the unique ID of the element you are looking for.
h1 is an Element object, 'h1' is a string.
滿天的星座2017-06-14 10:55:37
It depends on the situation that you are a beginner, so don’t make some confusing variable names. This is your own responsibility. For example:
var _h1 = document.createElement('h1');某草草2017-06-14 10:55:37
When creating a tag, + is used. When inserting, it is equivalent to h1 being a variable. It is not + at this time
伊谢尔伦2017-06-14 10:55:37
Without the representative symbol, it is a variable; with the representative symbol, it is a string
曾经蜡笔没有小新2017-06-14 10:55:37
var h1 = document.createElement('h1');h1 in this line is a variable, representing a newly created element. It will be easier to understand if you change the variable name.
var node = document.createElement('h1');
document.body.insertBefore(node,btn);