A question

Question

Array.prototype.func = () => return (this instance of Array);

alert((new Array()).func());

Why the output is false?

Does the __proto__ of new object not point to prototype of Array?

I have also tried to use "this.constructor==Array". But it doesn't work too. Does the constructor of prototype not point to Array class?

Answer 1

just ditch the arrow function and go back to the regular function:

Array.prototype.func = function() { return (this instanceof Array); };
alert((new Array()).func());

more about arrow func:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Functions/Arrow_functions

Answer 2

this points to the global object in arrow function.

Answer 3

An arrow functions doesn't have it's own this, thus rendering it not viable to be a method. In your code, this points to the Window object, which is not an instance of Array.

Make a function declaration like the other languages.