<HTML> <HEAD> <SCRIPT language="JavaScript"> <!-- function check_it() { var theurl=document.myForm.t1.value; var tomatch= /http:\/\/[A-Za-z0-9\.-]{3,}\.[A-Za-z]{3}/ if (tomatch.test(theurl)){ window.alert("URL OK."); return true; } else { window.alert("URL invalid. Try again."); return false; } } //--> </SCRIPT> </HEAD> <BODY> <FORM name="myForm" action="#" onSubmit="return check_it();"> Enter URL:<BR> <INPUT type="text" name="t1"> <BR> <INPUT type="submit" value="Submit"> </BODY> </HTML>