// JavaScript Document// JavaScript Documentfunction checkForm(){with (document.login) {	if (username.value == ""){		alert("You must enter a username.");		username.focus();	}	else if (password.value == ""){		alert("You must enter a password.");		password.focus();	}	else return true;}return false;}function isEmail(str) {	var supported = 0;	if (window.RegExp) {		var tempStr = "a";		var tempReg = new RegExp(tempStr);		if (tempReg.test(tempStr)) supported = 1;		}	if (!supported)		return (str.indexOf(".") > 2) && (str.indexOf("@") > 0);		var r1 = new RegExp("(@.*@)|(\\.\\.)|(@\\.)|(^\\.)");		var r2 = new RegExp("^.+\\@(\\[?)[a-zA-Z0-9\\-\\.]+\\.([a-zA-Z]{2,3}|[0-9]{1,3})(\\]?)$");	return (!r1.test(str) && r2.test(str));}