实例代码如下：
<code>
<script language="JavaScript">
<!--
function Validate(form) {
var v = new RegExp();
v.compile("^[A-Za-z]+://[A-Za-z0-9-_]+\\.[A-Za-z0-9-_%&\?\/.=]+$");
if (!v.test(form["URL"].value)) {
alert("You must supply a valid URL.");
return false;
}
}
//-->
</script>
<form name="MyForm" action="" method="POST" onsubmit="return Validate(this);">
<input type="TEXT" name="URL" value="http://">
<input type="SUBMIT" name="SUBMIT" value="SUBMIT">
</form>
</code>
