JQuery customizes the methods jquery.extend () and jquery.fn.extend (), where jquery.extend () can create global functions or selectors, and jquery.fn.extend () can create jQuery object methods.

Such as:

jQuery.extend({
showName : function(name){
alert(name)
}
});
jQuery.showName(" Deep blue ");

In addition to creating plug-ins, jQuery.extend() can be used to extend jQuery objects. Such as:

var a = {
name : "blue",
pass : 123
}
var b = {
name : "red",
pass : 456,
age : 1
}
var c = jQuery.extend({},a,b);

C has properties of object a and object b, and since object b is after object a, its name property takes precedence in object c.

The jQuery.extend() method passes a series of options for plug-ins, including default values.

function fn(options){
var options = jQuery.extend({ //List of default parameter options
name1 : value1,
name2 : value2,
name3 : value3
},options); //Use the function's arguments to override or merge into the default parameter options list
//The body of the function
}
fn({ name1 : value3, name2 : value2 , name3 : value1 });//Using the new values
fn({ name4 : value3, name5 : value2 });//Add new options by default
fn(); //Leave the default option values

When a new parameter value is passed when the method is called, the default parameter option value is overwritten; otherwise, the default parameter value is used.

Create JQuery object methods using JQuery.fn objects

You can add properties and methods with a jQuery. Fn object, which is actually attached to jQuery. Prototype.

What is fn. If you look at the jQuery code, it’s not hard to see.

jQuery.fn = jQuery.prototype = {

　　　init: function( selector, context ) {//....　

　　　//......

};

JQuery. Fn = jQuery. Prototype.

Such as:

jQuery.fn.test = function(){
alert(" This is a jQuery Object methods !");
}
jQuery("div").click(function(){
$(this).test(); //Call the test() method on the current jQuery object
});

We can create the jQuery object methods by calling the jquery.fn.extend () method.

jQuery.fn.extend({
test : function(){
return this.each(function(){
alert(this.nodeName)
});
}
});
jQuery("body *").click(function(){
$(this).test(); //Call the jQuery object method
});

In a word :jQuery. Extend is a custom extension to jQuery classes, and jQuery. Fn. Extend is a custom extension to jQuery objects.