JS中的instanceof和typeof

JS中的instanceof和typeof ：

http://wasabi.iteye.com/blog/179335

 

 疑问：

 

function f(){ return f; }

alert(new f());  // function f(){ return f; }

alert(new f() instanceof f);       //弹出结果是false；

 

function f(){ }

alert(new f());  //object

 alert(new f() instanceof f);     //弹出结果是true；

 

 

答案： ‘new’ returns an instance of the class, unless the function that defines the class returns something else that is an object. So in this case, new f() just returns the function f itself and not an instance of it.