getRandomNumbers.js

Utils = {
	// Shuffle array
	shuffle: function (o) {
		for(var j, x, i = o.length; i; j = Math.floor(Math.random() * i), x = o[--i], o[i] = o[j], o[j] = x);
			return o;
	},
	// Get random number in range
	getRandomInt: function (min, max) {
		return Math.floor(Math.random() * (max - min + 1)) + min;
	},
	// Random numbers
	// Requirements
	// * You need a set of random numbers
	// * The numbers need to be unique
	// * The order of the returned numbers needs to be random (optional)
	getRandomNumbers: function (count, min, max, shuffle) {
		max += 1;
		// Input parameters must meet these conditions
		if (max <= min || count < 0 || (count > max - min && max - min > 0)) {
			return false;
		}

		//  initialize set S to empty
		//  for J := N-M + 1 to N do
		//    T := RandInt(1, J)
		//    if T is not in S then
		//      insert T in S
		//    else
		//      insert J in S
		//
		var candidates = {};
		for (var top = max - count; top < max; top++) {
			var candidate = this.getRandomInt(min, top);
			if (!candidates[candidate]) {
				candidates[candidate] = true;
			} else {
				candidates[top] = true;
			}
		}

		var candidatesArray = Object.keys(candidates);

		// Shuffle candidates only if shuffle var is true
		if (shuffle) {
			candidatesArray = this.shuffle(candidatesArray);
		}

		return candidatesArray;
	}
};