Asynchronous Requests with JavaScript and Ajax

An anonymous reader writes "I rarely read an entire article about a single object, especially one that is this simple. However, you will use this object over and over again in each page and application that you write that uses Ajax. This article shows you how to create XMLHttpRequest instances in a cross-browser way, construct and send requests, and respond to the server."

Comments

If you like this, try too AJAX Developer's Journal

[jg21]

If you liked this article then you will surely like AJAX Developer's Journal , just launched digitally/online and replete with how-to articles and interviews, all freely available. It's edited by Rob Gonda.

Yeah, new news indeed

[masklinn]

I mean, the first articles explaining how to create cross-browsers XMLHTTP requests ain't have more than a pair of years anyway...

Wouldn't it be slightly more interresting if Slashdot promoted useful stuff such as the Dojo or Mochikit Javascript libraries/toolkits (others exist btw, those are just fairly stable and advanced), which actually:

• Make that kind of stuff easier
• Make that kind of stuff more reliable
• Give great tools/shortcuts for working with javascript
• Actually work

Just wondering...

Re:Yeah, new news indeed

[ChrisZermatt]

Better yet, QooxDoo. Best I come across so far, even though its still in its early stages...
http://qooxdoo.oss.schlund.de/

What to do with XML results?

[ccady]

Bah. That's easy. The business of creating and using an XMLHttpRequest is well-documented and easy to do. What is far less well documented is how to access the resulting XML as a cross-browser XML DOM object. (Accessing it as text is easy.)

How does one access the results 1) as an XML DOM, and 2) in a cross browser way. I am currently investigating Sarissa.

I challenge someone to come up with a good article on that!

Easier than the article

[esconsult1]

Just use the excellent prototype javascript library instead. Saves a ton of time. It's cross platform, dev language agnostic, and has super sweet functionality built in.

I guess you can use JSON, and XML data formats with prototype, but I just use plain old text to accomplish whatever I want.

Prototype is also used in Ruby on Rails and its PHP analogue CAKE, and also the excellent perl framework Catalyst

overriding the constructor

[ydnar]

With JavaScript, the object that is returned by the newoperator is the return value of the constructor. Which means you can set/override pretty much any object/property with a pseudo-constructor that returns any arbitrary object (class).

Adding XMLHttpRequest to Internet Explorer:

if( typeof window.XMLHttpRequest == "undefined" ) {
    window.XMLHttpRequest = function() {
        var types = [
            "Microsoft.XMLHTTP",
            "MSXML2.XMLHTTP.5.0",
            "MSXML2.XMLHTTP.4.0",
            "MSXML2.XMLHTTP.3.0",
            "MSXML2.XMLHTTP"
        ];

        for( var i = 0; i < types.length; i++ ) {
            try {
                return new ActiveXObject( types[ i ] );
            } catch( e ) {}
        }

        return undefined;
    }
}

y

Firefox AJAX Debugger

[Val314]

pretty usefull: https://addons.mozilla.org/extensions/moreinfo.php ?id=1843&application=firefox

"FireBug is a new tool that aids with debugging Javascript, DHTML, and Ajax. It is like a combination of the Javascript Console, DOM Inspector, and a command line Javascript interpreter."

thanks http://weblogs.mozillazine.org/gerv/archives/2006/ 01/firebug.html for the tipp