As shown below:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>在此处插入标题</title>
<script type="text/javascript">
//判断用户输入的电子邮箱格式是否正确
function checkEmail(){
var myforms=document.forms;
var myemail=myforms[0].email.value;
var myReg=/^[a-zA-Z0-9_-]+@([a-zA-Z0-9]+\.)+(com|cn|net|org)$/;
if(myReg.test(myemail)){
return true;
}else{
myspan.innerText="邮箱格式不对!";
return false;
}
}
</script>
</head>
<body>
<form action="#">
<table>
<tr><td>邮箱：<input type="text" id=email></td><td><span id=myspan style="text-size:18pt;color:red;"></span></td></tr>
<tr><td><input type="submit" value="提交" onclick="return checkEmail()"/></td><td></td></tr>
</table>
</form>
</body>
</html>
![[Web front-end] Node.js quick start](https://img.php.cn/upload/course/000/000/067/662b5d34ba7c0227.png)
