load_email_test.php
<?php
$ROOT_PATH = "";
require_once("includes/header.php");
include_once($ROOT_PATH."includes/common.php");
if($conn = mySQLConnect())
{
$mailid=$_GET['emval'];
$query=mysql_query("select * from usermaster where email='$mailid'");
if($row = mysql_fetch_array($query))
{
echo "Email Already Exists";
}
else
{
echo "Congrats ID Available";
}
}
?>

load_left.js

 

var xmlhttp;
var emailval;
var email = /^[^@]+@[^@.]+\.[^@]*\w\w$/;
function chemail(emailval)
{

xmlhttp=GetXmlHttpObject();
if (xmlhttp==null)
{
alert ("Your browser does not support XMLHTTP!");
return;
}
if (!email.test(emailval)) {
alert("Please Enter A Valid Email Address ")
document.getElementById('email').value="";
document.getElementById('email').focus();
email.style.backgroundColor = '#f1bcc9';
return false;
} else {

//email.style.backgroundColor = '#DCC5A9';

var url="load_email_test.php?emval="+emailval+"";
xmlhttp.onreadystatechange=stateChanged;
xmlhttp.open("GET",url,true);
xmlhttp.send(null);
}
}
function stateChanged()
{
if (xmlhttp.readyState==4)
{
////document.getElementById('left_msg').innerHTML=

xmlhttp.responseText;
if(xmlhttp.responseText=="Email Already Exists"){
document.getElementById('email').value="";
//document.getElementById('email').focus();
}
alert(xmlhttp.responseText);
}


}

function GetXmlHttpObject()
{
if (window.XMLHttpRequest)
{
// code for IE7+, Firefox, Chrome, Opera, Safari
return new XMLHttpRequest();
}
if (window.ActiveXObject)
{
// code for IE6, IE5
return new ActiveXObject("Microsoft.XMLHTTP");
}
return null;
}