Adding jQuery object methods

Most of jQuery's built-in functionality is provided through its object instance methods, and this is where plugins shine as well. Whenever we would write a function that acts on part of the DOM, it is probably appropriate instead to create an instance method.

We have seen that adding global functions requires extending the jQuery object with new methods. Adding instance methods is similar, but we instead extend the jQuery.fn object:

jQuery.fn.myMethod = function() { 
  alert('Nothing happens.'); 
}; 

Note

The jQuery.fn object is an alias to jQuery.prototype, provided for conciseness.

We can then call this new method from our code after using any selector expression:

$('div').myMethod(); 

Our alert is displayed (once for each <div> in the document) when we invoke the method. We might as well have written a global function, though, as we haven't used the matched DOM nodes in any way. A reasonable method implementation acts on its context.

Object method context

Within...