<html> <head> <script type="text/javascript"> function validate_email(field, alerttxt) { with (field) { apos = value.indexOf("@") dotpos = value.lastIndexOf(".") if (apos < 1 || dotpos - apos < 2) { alert(alerttxt); return false } else { return true } } } function validate_form(thisform) { with (thisform) { if (validate_email(email, "Not a valid e-mail address!") == false) { email.focus(); return false } } } </script> </head> <body> <form action="submitpage.htm"onsubmit="return validate_form(this);" method="post"> Email: <input type="text" name="email" size="30"> <input type="submit" value="Submit"/> </form> </body> </html>
原文：http://www.cnblogs.com/Teacher-chang/p/5659917.html