How do the ES6 Map shims work

Question

Based on my understanding of the docs (here and here) one would need a reference to the memory address for it to work:

const foo = {};
const map = new Map();
ma         


        

Answer 1

The trick is to store in an array and perform the lookup in O(n) time by iterating and using strict comparison—instead of using a true hash function which would be O(1) lookup. For example consider this:

var myObj = {};

var someArray = [{}, {}, myObj, {}];

console.log(someArray.indexOf(myObj)); // returns 2

Here is my implementation from another answer: Javascript HashTable use Object key

function Map() {
    var keys = [], values = [];

    return {
        put: function (key, value) {
            var index = keys.indexOf(key);
            if(index == -1) {
                keys.push(key);
                values.push(value);
            }
            else {
                values[index] = value;
            }
        },
        get: function (key) {
            return values[keys.indexOf(key)];
        }
    };
}