群内问题一粒 select change 事件 如果用vue数据双向绑定更简单；
代码语言：javascript复制<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1" />
<meta name="viewport" content="width=device-width, initial-scale=1.0,user-scalable=0">
<title>select change</title>
<script type="text/javascript" src="http://apps.bdimg.com/libs/jquery/2.1.4/jquery.min.js"></script>
</head>
<body>
<script type="text/javascript">
$(function(){
var num=0;
var len = 4;//显示的长度
$("#slct").change(function () {
num ;
num = parseInt(num, 10);
num = num.toString();
while(num.length < len) {
num = '0' num;
}
console.log(num)
$('#num').val(num)
})
})
</script>
<input type="text" id='num' value="0000" />
<select id='slct'>
<option value ="volvo">javascript</option>
<option value ="saab">sass</option>
<option value="opel">grunt</option>
<option value="audi">vue</option>
<option value="audi">jquery</option>
<option value="audi">bootstrap</option>
</select>
</body>
</html>
