Using Array objects as key for ES6 Map

Question

I am trying to update my code to ES6 as I am using Node 4.0 and really like its features so far. However I have problems with the new ES6 Map data structure as

Answer 1

You need to save a reference to the non-primitive instance of Array you used as a key. Notice the difference in the following two examples:

"use strict";

var a = new Map();
a.set(['x','y'], 1);
console.log(a.get(['x','y']));
console.log(['x','y'] === ['x','y']);

var b = new Map();
var array = ['x','y'];
b.set(array, 1);
console.log(b.get(array));
console.log(array === array);