//Gets the browser specific XmlHttpRequest Object
function getXmlHttpRequestObject() {
 if (window.XMLHttpRequest) {
    return new XMLHttpRequest(); //Mozilla, Safari ...
 } else if (window.ActiveXObject) {
    return new ActiveXObject("Microsoft.XMLHTTP"); //IE
 } else {
    //Display our error message
    alert("Your browser doesn't support the XmlHttpRequest object.");
 }
}

var returnedVal = 0;
var formObj = null;

//Our XmlHttpRequest object
var receiveReq = getXmlHttpRequestObject();

//Initiate the AJAX request
function makeRequest(url, param) {
//If our readystate is either not started or finished, initiate a new request
 if (receiveReq.readyState == 4 || receiveReq.readyState == 0) {
   //Set up the connection to captcha_test.html. True sets the request to asyncronous(default) 
   receiveReq.open("POST", url, true);
   //Set the function that will be called when the XmlHttpRequest objects state changes
   receiveReq.onreadystatechange = updatePage;

   //Add HTTP headers to the request
   receiveReq.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
   receiveReq.setRequestHeader("Content-length", param.length);
   receiveReq.setRequestHeader("Connection", "close");

   //Make the request
   receiveReq.send(param);
 }   
}

//Called every time our XmlHttpRequest objects state changes
function updatePage() {
 //Check if our response is ready
 if (receiveReq.readyState == 4) {
   //Set the content of the DIV element with the response text
	var phpVal = receiveReq.responseText;
	returnedVal = phpVal;
   //Get a reference to CAPTCHA imagealert(phpVal);
	if(phpVal == 1){
		if(check_Field(formObj)) {
			formObj.submit();
		}
	} else {
	   img = document.getElementById('imgCaptcha'); 
	   //Change the image
	   img.src = 'captcha-create-img.php?' + Math.random();
	   document.getElementById('result').innerHTML = "Your attempt to enter the characters from the image above was not successful. Please try again.";
	   formObj.txtCaptcha.value = "";
	}
 }
}

//Called every time when form is submitted
function getParam(theForm) {
 //Set the URL
 var url = 'captcha-verify.php';
 //Set up the parameters of our AJAX call
 var postStr = theForm.txtCaptcha.name + "=" + encodeURIComponent(theForm.txtCaptcha.value);
 //Call the function that initiate the AJAX request
 formObj = theForm;
 makeRequest(url, postStr);
 return false;
}