变量存储功能是基本类型还是引用类型？

Question

var f1 = function(){}

var f2 = f1; 

It pointed to the same function as f1 or it store another copy from f1?

Answer 1

The value of f2 is, like f1 , a reference to the same function.

You can use the fact that functions are objects to prove it :

 var f1 = function(){}
 var f2 = f1; 
 f1.a = 3;
 console.log(f2.a); // logs 3

But as you can't change a function core, there is little practical use in knowing this, apart the fact you don't use much memory if you duplicate a function reference.

Answer 2

It is really easy to prove using ===

var f1 = function(){}
var f2 = f1; 

console.log(f2===f1)

>>true

So f2 and f1 are pointing to the exact same function.