<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<script src="jquery-1.12.3.js" charset="utf-8"></script>
</head>
<body>
<input type="text" name="name" placeholder="请输入用户名"></br>
<input type="password" name="name" placeholder="请输入密码"></br>
<input type="submit" name="name" value="登录">
</body>
<script type="text/javascript">
//是用焦点和失去焦点事件处理
$('input').on("focus",function(){
//接受原有的placeholder的value；
var val = this.placeholder;
//获取焦点让placeholder为空；
this.placeholder = "";
//获取焦点才能失去焦点，所以失去焦点函写在获取焦点里面
$('input').on('blur',function(){
//失去焦点后，placeholder变回原有的值
this.placeholder = val;
})
});
</script>
</html>
上面为焦点事件
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style>
#div0{
width:700px;
height:500px;
border:3px #000000 solid;}
#div1{
width:300px;
height:200px;
float:left;
background-color:#CCCCCC;}
#div2{
width:300px;
height:200px;
float:right;
background-color:#F00;}
ul,li{
list-style: none;
}
ul li a{
display: block;
background:red;
border: 1px solid teal;
}
</style>
<script type="text/javascript">
window.onload=function(){
var oto1=document.getElementById('div1');
var oto2=oto1.getElementsByTagName('li');
var oto3=document.getElementById('div2');
var ul = document.getElementsByTagName('ul')[0];
ul.onclick = function(e){
//事件委托
var text = e.target.text;
//把值赋给div2的innerHTML；
oto3.innerHTML = text;
// 如果想让值内容累加，执行此代码,把上一行的代码注释掉
// oto3.innerHTML += text + "</br>";
}
}
</script>
</head>
<body>
<div id="div0">
<div id="div1">
<ul>
<li><a href="javascript:void(0)">oh my</a></li>
<li><a href="javascript:void(0)">2</a></li>
<li><a href="javascript:void(0)">3</a></li>
<li><a href="javascript:void(0)">4</a></li>
<li><a href="javascript:void(0)">5</a></li>
</ul>
</div>
<div id="div2"></div>
</div>
</body>
</html>