randomPick/randomNum

randomPick.js

/* need underscore.js */

/**
 * randomNum
 * randomNum(3,6); => 4
 */
var randomNum = function(from, to) {
	return from + Math.floor( Math.random() * (to - from + 1) );
};

/**
 * randomPick
 * randomPick([1,2,3,4,5], 3); => [3,5,2]
 */
var randomPick = function(array, length) {
	if(array.length === 0){
		return [];
	}
	var temp = _.clone(array);
	var ret = [];
	var item;
	for(var i=0, l=length; i<l; i++){
		item = temp[randomNum(0, temp.length-1)];
		ret.push(item);
		temp = _.without(temp, item);
		if(temp.length === 0){
			break;
		}
	}
	return ret;
};