代码如下
<html xmlns="
http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>无标题文档</title>
<script type="text/javascript" src="jquery-1.4.2.min.js"></script>
<script>
$(function(){
$('#btn').click(function(){
var length = $('#input').val().length;
alert(length);
if(length>10){
alert('太长');
return false
}
});
})
</script>
</head>
<body>
<input id="input" />
<input id="btn" type="button" value="长度"/>
</body>
</html>本回答被提问者采纳