var Css1={size: "10px",style: "oblique"} 
var Css2={size: "12px",style: "oblique",weight: "bolder"} 
$.jQuery.extend(Css1,Css2) 

//结果:Css1的size属性被覆盖,而且继承了Css2的weight属性 
// Css1 = {size: "12px",style: "oblique",weight: "bolder"} 

jQuery.extend( 
{ name: “John”, location: { city: “Boston” } }, 
{ last: “Resig”, location: { state: “MA” } } 
); 

 //结果：{ name: “John”, last: “Resig”, location: { state: “MA” } }

--深层合并
jQuery.extend( true, 
{ name: “John”, location: { city: “Boston” } }, 
{ last: “Resig”, location: { state: “MA” } } 
); 

//结果：
{ name: “John”, last: “Resig”, 
 location: { city: “Boston”, state: “MA” } }  

$.extend({ 
add:function(a,b){return a+b;}, 
minus:function(a,b){return a-b}, 
multiply:function(a,b){return a*b;}, 
divide:function(a,b){return Math.floor(a/b);} 
}); 

var sum = $.add(3,5)+$.minus(3,5)+$.multiply(3,5)+$.divide(5,7); 
console.log(sum); 

$.fn.extend({name:function(){console.log("1")},age:12})
a=$('body')
a.name() //1