Array.prototype.shuffle: Shuffles array using custom Array.createRandomSortFunction()

Array.shuffle.js

Array.createRandomSortFunction = () => {
	let map = new Map([]);

	let lookup = v => {
		if(map.get(v)) return map.get(v);
		let o = Math.random();
		map.set(v, o);
		return o;
	}

	return (a, b) => lookup(a) - lookup(b);
};

Array.prototype.shuffle = function(){
	return this.sort(Array.createRandomSortFunction());
}