From jQuery JavaScript Library

Contents 1 Coding Style 1.1 Indenting Code 2 Widgets 3 Conformance 3.1 Callbacks 3.2 Derivations from other classes 3.3 Templating 3.4 Behaviour 3.5 Object oriented structure 4 Documentation 4.1 Javadoc blocks 4.2 Inline commenting 5 Tip's and Tricks

Coding Style

Indenting Code

Please try to indent code using tabs only. It makes work much easier, because you can change your own tab size in your own editor if the indenting is too large for your view. But it's not so easy to change whitespace indents.

Widgets

ui.core.js provides a factory method to create widget classes. The signature is $.widget(name, Options prototype).

Calling the factory creates a plugin method used to create and interact with an instance of that widget class.

Available methods for each instance, in addition to those provided by the prototype argument:

• destroy(): Removes the instance from the encapsulated DOM element, which was stored on instance creation
• getData/setData/data(String key[, String value]): Gets or sets an option for this instance
• enable(): Set disabled option to false, its up to the instance to respect the option
• disable(): Set disabled option to true, its up to the instance to respect the option

Available properties for each instance:

• options: The options for this widget instance, usually a mix of defaults with settings provided by the user
• element: A jQuery object always containing a single DOM element, which can be accessed with this.element[0].

Usage:

 $.widget("ui.mywidget", {
   init: function() {
     // init code for mywidget
     // can use this.options
     if (this.options.hidden) {
       // and this.element
       this.element.hide(); 
     }
   },
   doSomething: function() {
      // manipulate the widget
   },
   value: function() {
     // calculate some value and return it
     return calculate();
   },
   length: function() {
      return someOtherValue();
   }
 });
 $.ui.mywidget.getter = "value length";
 $.ui.mywidget.defaults = {
   option1: "defaultValue",
   option2: 123
 };

Every UI plugin uses the widget factory, so for full references, check out any code from UI, eg. sortable.js.

Conformance

Callbacks

Please think about possible callbacks wherever possible. They should be named closer to jQuery-style, instead of DOM like, draggable for instance has the following callbacks:

• start
• drag
• stop

and would be bound to like so:

 {
   start: function(){},
   drag: function(){},
   stop: function(){}
 }

Rather than using your own functions to call these callbacks, jQuery's trigger method was updated for UI to makes life easier and should be used all over the place:

$(this.element).triggerHandler(longname, [e, obj], this.options[name])

where longname is the callback's name together with a prefix (action of your plugin) (i.e. "dragstart"), this.element is the current element, e is the browser event, and obj should be an object holding your own key/value pairs that you want to pass to the callback. this.options[name] is the user's callback function (so this would be without prefix).

In case of resizables, this would be:

$(this.element).triggerHandler('resizestop', [e,that.prepareCallbackObj(this)], o.stop);

that.prepareCallbackObj is only a convenience method that prepares the object. The user's function supplied with the callback now gets unified arguments: the first argument is the browser event (e), the second argument is the object.

Please look at one of the mouse interaction implementations (Resizables for example) to get a direct view how to implement this stuff.

Derivations from other classes

All plugins related to mouse interaction make use of another class, the mouse interaction class. It basically handles all events (mousedown,mouseup,mousemove) and bindings, and you can use private callbacks to then do something with the new mouse position (move the element for example).

Look at the implementation of draggables/resizables for a self-explanatory view.

Templating

Coming soon!

Behaviour

Coming soon!

Object oriented structure

Please try to use a object oriented structure wherever it makes sense. Look at drag & drop for how it's made - without using prototypes in Draggables, I would have had the need to attach properties to every DOM node. It makes much more sense this way.

Documentation

Javadoc blocks

Please do not generate javadoc blocks for your functions and classes anymore, but write the real documentation into our wiki at UI.

Inline commenting

Put inline comments before the line they comment and a space between the doubleslash and the comment text.

Comment the "why" things are done, not "how". The "how" is provided by the code. Document things that aren't obvious from the code.

// only left click starts dragging
if (e.which != 1)
  return true;

In this example, it's hard to guess what this prevention is for (until you know how the e.which property works), so an explanation doesn't hurt here.

Tip's and Tricks

• Coming soon

DHTML style guide