Ajax using php email validation

put this script on html head.....

div class='k'> Type input. Rule:type email formate only.

type ur email here << input type="text" onkeyup= prompt(this.value)" size="20" />
Prompt: /div>
the above is a html form.....save any name .htm or phpand php code is
$z=$_GET["q"];echo $z;if (!preg_match("/^[_a-z0-9-]+(.[_a-z0-9-]+)*@[a-z0-9-]+(.[a-z0-9-]+)*(.[a-z]{2,3})$/i", $z)){echo still Invalid email";}else{echo Valid Email";} ?>
the abvoe is the expresstion match via php save this file has filter.php