custom array-like object looks like true array

I have custom array-like object, with all the array methods, which acts as an array, but Object.prototype.toString.call(myArrayLikeObj) returns [object Object] not [object Array]

How to prepare my object to return [object Array]?

Can I see somewhere Object.toString source code?

>Solution :

Symbol.toStringTag is the well-known name of the "tag" you want:

YourCustomArrayPrototype[Symbol.toStringTag] = () => 'Array'; // Sure, why not?

That said, if you extend Array you will get this for free:

class MyCustomArray extends Array {}

console.log(
  Object.prototype.toString.call(new MyCustomArray(3))
); // Logs [object Array]