<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
</head>
<body>
<button>点击</button>
<p>abc</p>
<div class="inner"></div>
<div class="create"></div>
<script>
// window.onload = function() {
// document.write('<div>123</div>');
// }
// 三种创建元素方式区别
// 1. document.write() 创建元素 如果页面文档流加载完毕，再调用这句话会导致页面重绘
// var btn = document.querySelector('button');
// btn.onclick = function() {
// document.write('<div>123</div>');
// }
// 2. innerHTML 创建元素
var inner = document.querySelector('.inner');
// for (var i = 0; i <= 100; i++) {
// inner.innerHTML += '<a href="#">百度</a>'
// }
var arr = [];
for (var i = 0; i <= 100; i++) {
arr.push('<a href="#">百度</a>');
}
inner.innerHTML = arr.join('');
// 3. document.createElement() 创建元素
var create = document.querySelector('.create');
for (var i = 0; i <= 100; i++) {
var a = document.createElement('a');
create.appendChild(a);
}
</script>
</body>
</html>
innerHTML拼接效率测试:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>效率测试</title>
</head>
<body>
</body>
<script>
function fn() {
var d1 = +new Date();
var str = '';
for (var i = 0; i < 1000; i++) {
document.body.innerHTML += '<div style="width:100px; height:2px; border:1px solid blue;"></div>';
}
var d2 = +new Date();
console.log(d2 - d1);
}
fn();
</script>
</html>
innerHTML数组效率测试:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>效率测试</title>
</head>
<body>
</body>
<script>
function fn() {
var d1 = +new Date();
var array = [];
for (var i = 0; i < 1000; i++) {
array.push('<div style="width:100px; height:2px; border:1px solid blue;"></div>');
}
document.body.innerHTML = array.join('');
var d2 = +new Date();
console.log(d2 - d1);
}
fn();
</script>
</html>
createElement效率测试:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>效率测试</title>
</head>
<body>
</body>
<script>
function fn() {
var d1 = +new Date();
for (var i = 0; i < 1000; i++) {
var div = document.createElement('div');
div.style.width = '100px';
div.style.height = '2px';
div.style.border = '1px solid red';
document.body.appendChild(div);
}
var d2 = +new Date();
console.log(d2 - d1);
}
fn();
</script>
</html>