Cesar D. Rodas

Today, the trend is to implement AJAX in everything related with Web. AJAX (Asynchronous JavaScript and XML) is not a new programming language, It is a “style” of development that mix two technologies, the client side (JavaScript) and the server site (usually PHP, JSP, Java or other).

The client side could request just a part of the page instead of download the hole page. Until this point everything is good, but not always is so good, such benefits needs more development, and AJAX is not well standarized.

Let’s start with AJAX:

Basic Example

Html:

<!– Clicking this link initiates the asyncronous request –>
<a href=“javascript:void(0)” onclick=“supportAjax && sayHello();”>Say Hello</a><br />
<!– used to display the results of the asyncronous request –>
<span id=“span_result”></span>

Javascript:

var supportAjax;

function createAjaxObj() {
       supportAjax=true;
       if (window.XMLHttpRequest) {
           return new XMLHttpRequest(); //Not IE
       } else if(window.ActiveXObject) {
           return new ActiveXObject(“Microsoft.XMLHTTP”); //IE
       } else {
           supportAjax=true;
       }
}

var receiveReq = createAjaxObj();
function sayHello() {
	//If our XmlHttpRequest object is not in the middle
        //of a request,
        //start the new asyncronous call.
	if (receiveReq.readyState == 4 ||
                   receiveReq.readyState == 0) {
		//Setup the connection as a GET call to
                //SayHello.php.
		//True explicity sets the request
                //to asyncronous (default).
		receiveReq.open(“GET”, ‘SayHello.php’, true);
		//Set the function that will be called when the
                //XmlHttpRequest objects state changes.
		receiveReq.onreadystatechange = handleSayHello;
		//Make the actual request.
		receiveReq.send(null);
	}
}
//Called every time our XmlHttpRequest objects state changes.
function handleSayHello() {
	//Check to see if the XmlHttpRequests state is finished.
	if (receiveReq.readyState == 4) {
		//Set the contents of our span element to
                // the result of the asyncronous call.
		elem = document.getElementById(’span_result’);
                elem.innerHTML = receiveReq.responseText;
	}
}

As you can see write AJAX pages is not so short, Image that you have to do a Web Portal such as Yahoo Mail, Gmail, or something else that require a heavy use of AJAX.

I usually work with Javascript class that made easy develop AJAX apps.

Download AJAX Javascript

And Here is an example how to implement this JS class:

<script  language=“JavaScript1.1“ src=“ajax.js“></script>
<script language=“JavaScript1.1“>
    function ajax_process_ok(obj)
    {
	//do something, the text
	// is in “obj.responseText”
    }

    function ajax_process_err(obj)
    {
        //do something
    }

    /*
     *	This is the function that has the ajax function
     */
    function AjaxQuery()
    {
        //sucess function handler
        var success  = function(t){ajax_process_ok(t);}
        //error function handler
        var failure  = function(t){ajax_process_err(t);}
        var url = “./hellopage.php“;
        var myAjax = new Ajax.Request(url,
            {
                method:‘get‘,  onSuccess:success,
                onFailure:failure
            }
        )
    }

</script>

BTW, there exist others simplest method to write AJAX Apps, but I dont know to use it, I reccoment to visit PHP: Writing XAJAX and Smarty Templates

Also I’ve listening many goods things about scriptaculous, prototype, and don´t forgot to check these too

Also I recomment to see the PHP AJAX Section

• Hippo AJAX Form: Generate HTML forms and submit via AJAX.
• True Color Picker: Present a palette to let the user pick colors.
• AJAX Edit In Place: Edit and save a paragraph of text in an HTML page.
• AJAX File Uploader: Browse files uploaded without page reloading.
• AJAX Grid: Edit and save table data without page refreshing.
• Auto complete: Auto-complete text typed in a form input.
• Suggester: Complete text typed in form inputs using AJAX

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This entry was posted on Thursday, July 5th, 2007 at 3:10 pm and is filed under General, PHP, servers, phpclasses, ajax. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.