permutations.js

		function cycle(array) {
			function cycleInt(array, count) {
				if (count == array.length) return [];
				var tmp = array.slice(0);
				tmp.push(tmp.shift());
				return cycleInt(tmp, count + 1).concat([tmp]);
			}
			return cycleInt(array, 0);
		}
		function flatten(col) {
			return col.reduce(function(pv, cv) {
				return pv.concat(cv);
			}, [])
		}
		function permutations(array) {
			if (array.length <= 1) return array;
			return flatten(
				cycle(array)
					.map(function(c) {
						return permutations(c.slice(1))
							.map(function(p) {
								return [c[0]].concat(p);
							})
					})
			);
		}