shuffle.js

/**
 * Randomly shuffle an array
 * https://stackoverflow.com/a/2450976/1293256
 * @param  {Array} array The array to shuffle
 * @return {Array}       The shuffled array
 */
function shuffle (array) {

	let currentIndex = array.length;
	let temporaryValue, randomIndex;

	// While there remain elements to shuffle...
	while (0 !== currentIndex) {
		// Pick a remaining element...
		randomIndex = Math.floor(Math.random() * currentIndex);
		currentIndex -= 1;

		// And swap it with the current element.
		temporaryValue = array[currentIndex];
		array[currentIndex] = array[randomIndex];
		array[randomIndex] = temporaryValue;
	}

	return array;

}