Object.constructor() vs Array.prototype.join() in terms of performance : I've been reading this thread to check if object is an array or not.

> http://stackoverflow.com/questions/4775722/check-if-object-is-array?rq=1

The solution mentioned is:

    function isArray(obj){
        return !!obj && Array === obj.constructor;
    }

But I've written the following function

    function isArray(obj) {
         return obj.split;
    }

I've done some sample test. I'm finding array.join() returns faster result than object.constructor(). Am I missing something?

**I thought Object.constructor() is the parent class hence faster, but I'm able to return faster results using obj.split. Does it mean the answer in the other SO post was incorrect?**

**Jsfiddle:**

> https://jsfiddle.net/vdpseotp/6/

Please explain.