The role and difference of $.extend and $.fn.extend of jquery

jquery has two methods for developing plug-ins, namely:

JQuery.fn.extend ();

Jquery.extend ();

Although JavaScript does not have a clear class concept, it is more convenient to use a class to understand it.

jquery is a well-encapsulated class, such as we use the statement $ ("#btn1") to generate an instance of the jquery class.

Jquery.extend (object); Adding a class method to the jquery class can be understood as adding a static method. Such as:

jQuery.extend({


min: function(a, b) { return a < b ? a : b; },


max: function(a, b) { return a > b ? a : b; }


});

jQuery.min(2,3); //  2 
jQuery.max(4,5); //  5

Objectjquery. Extend (Target, Object1, [objectn]) extends an object with one or more other objects, returning the extended object
var settings = { validate: false, limit: 5, name: "foo" }; 
var options = { validate: true, name: "bar" }; 
jQuery.extend(settings, options);
Results:settings == { validate: true, limit: 5, name: "bar" }

JQuery.fn.extend (object); The extension to Jquery.prototype is to add "member functions" to the jquery class. An instance of the jquery class can use this "member function".

For example, we want to develop a plugin, make a special edit box, when it is clicked, then alert the contents of the current edit box. You can do this:

$.fn.extend ({          
      Alertwhileclick:function () {            
            $ (This). Click (function () {                  
                   alert ($ (this). Val ());            
             });            
      }       
});        
$ ("#input1"). Alertwhileclick ();  //page:     

$ ("#input1") is a jquery instance, and when it calls the Member method Alertwhileclick, it implements the extension, which pops up the contents of the current edit each time it is clicked.

The role and difference of $.extend and $.fn.extend of jquery