What does jQuery.fn mean?

Question

What does the fn here mean?

jQuery.fn.jquery 

Answer 1

In jQuery, the fn property is just an alias to the prototype property.

The jQuery identifier (or $) is just a constructor function, and all instances created with it, inherit from the constructor's prototype.

A simple constructor function:

function Test() {   this.a = 'a'; } Test.prototype.b = 'b';  var test = new Test();  test.a; // "a", own property test.b; // "b", inherited property 

A simple structure that resembles the architecture of jQuery:

(function() {   var foo = function(arg) { // core constructor     // ensure to use the `new` operator     if (!(this instanceof foo))       return new foo(arg);     // store an argument for this example     this.myArg = arg;     //..   };    // create `fn` alias to `prototype` property   foo.fn = foo.prototype = {     init: function () {/*...*/}     //...   };    // expose the library   window.foo = foo; })();  // Extension:  foo.fn.myPlugin = function () {   alert(this.myArg);   return this; // return `this` for chainability };  foo("bar").myPlugin(); // alerts "bar"