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The ultra lightweight JavaScript library


AJS is a ultra lightweight JavaScript library that is around 2 years old. It is inspired by MochiKit, but differs by being small and expressive. The current version is only 33 KB (uncompressed!), whereas MochiKit and other libraries such as JQuery, Mootools or Prototype is over/around 100 KB.

AJS includes:

  • Powerful and easy to use AJAX functions
  • Performance on almost everything
  • Effects
  • Drag and drop
  • Functional programming such as, AJS.partial
  • DOM functions such as AJS.$
  • AJAX JSON support (with AJS.loadJSON and AJS.serializeJSON)
  • Unified position and size that works in all the modern browsers
  • Unified events that work in all the modern browsers
  • and a lot more...

But that's not all! AJS also features:

  • Only ONE namespace is used, namely AJS
  • Documentation and examples on all functions
  • Polymorphic - A Python script can scan your code, find the AJS functions you use and create a special AJS file for you that is MUCH smaller!

Code snippets

Creating DOM smartly

var p_elm = P(SPAN({class: 'blue_n_black'}, IMG({src: 'hottie.gif'})));


//Delete all span elements with class "name" and fluffy_id element
removeElement($bytc('span', 'name'), $('fluffy_id'));

AJAX done easily

function doSearch() {
    var url = "";
    var d = AJS.loadJSON(url);

    d.addCallback(function(o) { alert(o); });
    d.addErrback(function(err) { alert(err); });

    var form = AJS.$('formy');
    d.sendReq({appid: "YahooDemo",
                        query: AJS.$f(form, 'q').value,
                        results: AJS.$f(form, 'r').value,
                        output: "json"})
    return false;


AJS.fx.setHeight(AJS.$('div'), {from: 0, to: 500});



Blog posts

Browsers supported

  • Firefox 1,0 and 1.5
  • IE 5.5 and 6.0
  • Netscape 7
  • Safari
  • Opera 8.5 and 9
  • And others...

Where it's used?

Download newest version of AJS

This zip file includes AJS.js,, documentation and examples:


Change log

Change log for AJS

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