<!DOCTYPE html>
<html>
<head lang="en">
<meta charset="UTF-8">
<title></title>
<script src="js/jquery-2.1.4.js"></script>
<script>
$(function(){
$("#sub").bind("click",function(event){
var username=$("#username").val();
if(username==""){
$("#msg").html("<p>文本值不能为空</p>");
event.preventDefault();//阻止默认行为(跳转、提交等)和stopprapagation()停止冒泡,可简写为return false;
}
});
})
</script>
</head>
<body>
<form action="test.html">
用户名:<input type="text" id="username" />
<input type="button" id="sub" value="提交" />
</form>
<div id="msg"></div>
</body>
</html>