A brief discussion on the difference between jquery.fn.extend and jquery.extend_jquery

1.jquery.extend(object); To extend the jQuery class itself. Add new methods to the class.
jquery.fn.extend(object); Add methods to jQuery objects.

$.extend({ 
　　add:function(a,b){return a+b;} 
}); 

//$.add(3,4);
//return 7 

jQuery adds a "static method" called add, and then you can use this method where jQuery is introduced.

2.jQuery.fn.extend(object); To extend jQuery.prototype is to add "member functions" to the jQuery class. Instances of the jQuery class can use this "member function".

$.fn.extend({ 
  alertClick:function(){ 
    $(this).click(function(){ 
      alert($(this).val()); 
    }); 
  } 
}); 

//页面上为：
<input id="input1" type="text"/>    

//使用
$("#input1").alertClick();  

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