/*

	This is the JavaScript file for the How to Create CAPTCHA Protection using PHP and AJAX Tutorial



	You may use this code in your own projects as long as this 

	copyright is left in place.  All code is provided AS-IS.

	This code is distributed in the hope that it will be useful,

 	but WITHOUT ANY WARRANTY; without even the implied warranty of

 	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

	

	For the rest of the code visit http://www.WebCheatSheet.com

	

	Copyright 2006 WebCheatSheet.com	



*/

//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.");

 }

}



//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; 



   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

   document.getElementById('result').innerHTML = receiveReq.responseText;

   //Get a reference to CAPTCHA image

   img = document.getElementById('imgCaptcha'); 

   //Change the image

   img.src = 'create_image.php?' + Math.random();

 }

}

function updatePage_post() {

 //Check if our response is ready

 if (receiveReq.readyState == 4) {

   //Set the content of the DIV element with the response text
	
   document.getElementById('result').innerHTML = receiveReq.responseText;

   //Get a reference to CAPTCHA image

   //img = document.getElementById('imgCaptcha'); 

   //Change the image

  // img.src = 'create_image.php?' + Math.random();

 }

}


function makeRequest_post(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_post; 



   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 when form is perfomed

function getParam(theForm) {

 //Set the URL

 var url = 'captcha.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

 makeRequest_post(url, postStr);
 }