function formValidation(thisform)
{
	
	with (thisform)
	{
		if(fname.value=="Name")fname.value=""; 
		if(fname.value=="")
		{
			alert("Please give us your name");
			fname.focus();
			return false;
		}
		if(phone.value=="Phone")phone.value=""; 
		if(phone.value=="")
		{
			alert("Please give us your phone number");
			phone.focus();
			return false;
		}
		
		
		if(email.value=="Email")email.value=""; 
		if(email.value=="")
		{
			alert("Please give us your email id");
			email.focus();
			return false;
		}
		if(emailvalidation(email,"Invalid email id")==false)
		{
			email.select();
			email.focus();
			return false;
		}
		if (comments.value=='Comments')comments.value="";  
		if(comments.value=="")
		{	
			alert("Please give us your comments");
			comments.select();
			comments.focus();
			return false;
		}
		if(userdigit.value=="Enter Verification code")userdigit.value="";
		if(userdigit.value=="") 
		{
		alert("Please enter verification code");
		userdigit.select();	
		userdigit.focus();
		return false;
		}	
			
		runAjax('check_captcha','process_mail.php',thisform.userdigit.value);
		return false;
	}	
	
	//thisform.submit();
}
function captcha_refresh()
{	
document.getElementById("button_div1").src='button.php?'+Math.random();
return false;
}
	<!--Ajax for checking the captcha code ends here -->

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

	function check_captcha() 
	{ 
		if (xmlHttp.readyState==4 || xmlHttp.readyState=="complete")
		{ 
			
				if(xmlHttp.responseText=="yes")
				{
					document.quickContactForm.submit();
				}
				else
				{
					captcha_refresh();
					document.quickContactForm.userdigit.value="Invalid Verification Code";
					document.quickContactForm.userdigit.focus();
					document.quickContactForm.userdigit.select();
					return false;
				}
		} 
	} 

	function GetXmlHttpObject()
	{ 
	var objXMLHttp=null
					if (window.XMLHttpRequest)
					{
						objXMLHttp=new XMLHttpRequest()
					}
					else if (window.ActiveXObject)
					{
						objXMLHttp=new ActiveXObject("Microsoft.XMLHTTP")
					}
		return objXMLHttp
	}

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