行为 样式 结构相分离的页面
JS CSS HTML
DOM 0写法
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<table border="1" width="300px">
<tr onmousemove="t1(0);" onmouseout="t2(0)"><td>1</td><td>2</td><td>3</td></tr>
<tr onmousemove="t1(1);" onmouseout="t2(1)"><td>1</td><td>2</td><td>3</td></tr>
<tr onmousemove="t1(2);" onmouseout="t2(2)"><td>1</td><td>2</td><td>3</td></tr>
</table>
<script>
//DOM 0实现的效果
function t1(n){
var mytrs = document.getElementsByTagName('tr')[n];
console.log(mytrs);
mytrs.style.backgroundColor = "red";
}
function t2(n){
var mytrs = document.getElementsByTagName('tr')[n];
console.log(mytrs);
mytrs.style.backgroundColor = "";
}
</script>
</body>
</html>
DOM 1写法
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<style>
.c1{
background-color: cadetblue;
300px;
}
</style>
<body>
<div class="c1">
<table border="1" width="300px">
<tr><td>1</td><td>2</td><td>3</td></tr>
<tr><td>1</td><td>2</td><td>3</td></tr>
<tr><td>1</td><td>2</td><td>3</td></tr>
</table>
</div>
<script>
//DOM 1实现的效果
var myTrs = document.getElementsByTagName("tr");
var len = myTrs.length;
for(var i=0;i<len;i++){
myTrs[i].onmouseover = function(){ //绑定事件
this.style.backgroundColor = "red"; //谁调用这个函数,这个this就指向谁
}
myTrs[i].onmouseout = function(){
this.style.backgroundColor = "";
}
}
</script>
</body>
</html>
第一种非常低效，每次都要在标签上绑定。
第二种相对高效一点，首先获取DOM对象，然后一次绑定。