jQuery无new创建对象原理

// jQuery 无new 创建对象套路

(function(g,undefined){

   var foo = function(){
     return new foo.fn.init();
   };

   foo.prototype = {

     saySth: function(){
       console.log("say something");
     },

     init: function(){
       console.log("inited");
       return this;
     }

   };

   foo.fn = foo.prototype;

   foo.fn.init.prototype = foo.fn;   // 关键点
   window.foo = foo;  
})(window);

var o = foo();
o.saySth();  // 输出say something