function validateForm(thisform)
{  
	with(thisform)
	{
	
		if(emptyvalidation(name,"Please Enter Name")==false)
		{
		name.focus();
		return false;
		}
		if(emptyvalidation(city,"Please Enter City")==false)
		{
		city.focus();
		return false;
		}
		if(emptyvalidation(phone,"Please Enter Phone Number")==false)
		{
		phone.focus();
		return false;
		}
		if(emptyvalidation(email,"Please Enter Email Address")==false)
		{
		email.focus();
		return false;
		}
		if(emailvalidation(email)==false)
		{
		alert("Invalid Email Address");
		email.select();
		email.focus();
		return false;
		}
		if(emptyvalidation(comments,"Please Enter Comments")==false)
		{
		comments.focus();
		return false;
		}
		if(emptyvalidation(userdigitcontact,"Please Enter Verification code")==false) 
		{
		userdigitcontact.select();	
		userdigitcontact.focus();
		return false;
		}	
		runAjax1('check_captcha1','process_contactmail.php',thisform.userdigitcontact.value);
		return false;
	}
}
function captcha_refresh1()
{	
document.getElementById("button_div1").src='buttoncontact.php?'+Math.random();
return false;
}
	<!--Ajax for checking the captcha code ends here -->

		var xmlHttp
		function runAjax1(field,argurl,argVal)
		{
		//document.getElementById("check_captcha").innerHTML=" Loading...";
		xmlHttp=GetXmlHttpObject1()
					if (xmlHttp==null)
					{
					alert ("Browser does not support HTTP Request")
					return
					} 
		var url=argurl
		url=url+"?userdigitcontact="+argVal
		url=url+"&sid="+Math.random()
		if(field=='check_captcha1')
		xmlHttp.onreadystatechange=check_captcha1;
		xmlHttp.open("GET",url,true)
		xmlHttp.send(null)
		}

	function check_captcha1() 
	{ 
		if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete")
		{ 
			
				if(xmlHttp.responseText=="yes")
				{
					document.contactUs.submit();
				}
				else
				{
					captcha_refresh1();
					document.contactUs.userdigitcontact.value="Invalid Verification Code";
					document.contactUs.userdigitcontact.focus();
					document.contactUs.userdigitcontact.select();
					return false;
				}
		} 
	} 

	function GetXmlHttpObject1()
	{ 
	var objXMLHttp=null
					if (window.XMLHttpRequest)
					{
						objXMLHttp=new XMLHttpRequest()
					}
					else if (window.ActiveXObject)
					{
						objXMLHttp=new ActiveXObject("Microsoft.XMLHTTP")
					}
		return objXMLHttp
	}
//document.contactUs.name.focus();
function emptyvalidation(entered, alertbox)
		{
				
			with (entered)
			{
				
			
				while (value.charAt(0) == ' ')
					value = value.substring(1);
				while (value.charAt(value.length - 1) == ' ')
					value = value.substring(0, value.length - 1);
				if (value==null || value=="")
				{
					if (alertbox!="") alert(alertbox);
					return false;
				}
				else return true;
			}
		}

   
function emailvalidation(entered,alertbox)
{
	with (entered)
	{
		lastpos=value.length-1;//Total Letters
		apos=value.indexOf("@"); //Total letters before @
		dotpos=value.lastIndexOf(".");//Total letters before .
		beforeStr=value.substring(0,apos);
		afterStr=value.substring(apos);
		dotafatpos=afterStr.indexOf(".");
		udslpos=beforeStr.lastIndexOf("_");
		dotfpos=beforeStr.indexOf(".");
		dotlpos=beforeStr.lastIndexOf(".");
		if (apos<1 || dotpos-apos<2 || lastpos-dotpos>3 || lastpos-dotpos<2 || dotfpos!=dotlpos || apos-1==udslpos || dotafatpos==1) 
		{if (alertbox) {alert(alertbox);} return false; }
		else {return true;}
	}
}