xxxxxxxxxx<html><head><meta charset="utf-8"><title>W3Cschool教程(w3cschool.cn)</title></head><head><script>function validateForm(){ var x=document.forms["myForm"]["email"].value; var atpos=x.indexOf("@"); var dotpos=x.lastIndexOf("."); if (atpos<1 || dotpos<atpos+2 || dotpos+2>=x.length){ alert("不是一个有效的 e-mail 地址"); return false; }}</script></head><body> <form name="myForm" action="demo-form" onsubmit="return validateForm();" method="post">Email: <input type="text" name="email"><input type="submit" value="提交"></form> </body></html>