# $(”div”).draggable() creates a draggable

# $(”div”).draggable(”destroy”) destroys it

Am I missing something here, or is that an extremely ugly design choice? Passing strings into functions to specify what function you want? eugh

I think they ended up having to do that because of jQuery's chaining support. Most of jQuery's functionality lives in a single namespace (jQuery.fn) which means you can chain method calls together like this:

jQuery('div:first').addClass('hello').text('Hello World').draggable().css('color', 'red');

If a plugin needs three or four methods, that's three or four extra functions on the one object - which ends up looking quite ugly:

jQuery('blah').draggable({options}).destroyDraggable()

The message passing idiom lets them add just one method to the jQuery.fn namespace that can cover a full range of different actions. I think it's a pretty clever pragmatic solution.

I really like this DSL aspect of jQuery!

I wonder however if a plugin could define its own namespace, like:

    $('blah').draggable().create({options}).css(..)...
    $('blah').draggable().destroy().css(..)...

draggable() returns a wrapper that exposes only the dragging specific methods, but the underlying jQuery is passed through and returned by any method called on the wrapper. That way you don't have to add all methods in the same namespace.

On second thought I don't know if this wouldn't just be confusing :-)

I still don't like it in terms of taste. I guess one question would be how does it handle a typo in the string.

If you call a.destroooooy() then you'll get a js error, but if you call a.execute("destroooooy")...

They'll both be run-time errors, hopefully they throw an exception.

The "sortables" have been using these arguments, I was a bit confused by them when I read the documentation, but now it seems okay.

It's called message passing. It used to be part of the commonly accepted definition of OO.

Sure. I still think it's ugly though. It reminds me a lot of an old coworkers code. He decided to simply expose one method to his subsystem - .execute(String what, String[] args) Then you would pass in strings to specify what you wanted it to do. It made my brain hurt for weeks.

I don't see how it is more like message passing than an ordinary method call? Only difference AFAICT is that since JS don't support "catch-alls" (yet), you can't handle missing methods at the receiver. But that does not seem to be relevant here.

I haven't had the chance to use jQuery, how does it compare to other JavaScript libraries such as MooTools or Prototype?

One big difference is that both Prototype and mooTools make modifications to the built-in types (extra Array methods etc). jQuery (and Dojo and YUI) explicitly avoids doing this for compatibility reasons. It's no coincidence that mooTools and Prototype are the only two big libraries that can't co-exist on a single page.

The interesting thing about jQuery is its focus - it almost exclusively works to improve the interaction between JavaScript and HTML. DOM manipulation is more convenient in jQuery than any other library, and the other library features build on top of that core ideal.

mooTools and Prototype attempt to make improvements to the JavaScript language. jQuery tends to play along with the language - it supports a functional style of programming using lots of closures (while you can avoid them if you really want to I find jQuery code with closures flows really well).

It's the abundant use of Closures is what brought me to jQuery in the first place. Like you I favor this approach

$('div').draggable().create({Object hash}).draggableDestroy();

It may look awkward at first but I think it will a result into a new win in the long run. I'm having alot of trouble downloading the new library for some reason but can you do something like this?

$('div').draggable().create({Object hash},function(){ alert(Object Creation confirmed}; ).draggableDestroy();

I think the ability to launch a callback function on the creation of a object could open oppurtunities for better UI feel and responsiveness.

Having had the chance to use MooTool and Prototype. I find jQuery the most expressive and matches my way of thinking. Granted it has it's roots in Prototype. But Prototype was never this fun to use and develop in. You just grab something from the DOM and manipulate all you like. A very lovely API.

news.yc poll on JS libs:

http://news.ycombinator.com/item?id=211630

I've used prototype and ExtJS extensively and am now giving jquery a try. From what I can see so far the structuring around the jQuery object makes it much easier for developers to do progressive enhancement as default rather than creating functionality that works only with JS enabled.