phpjs/functions/array/array_rand.js

php.js offers community built php functions in javascript

function array_rand(input, num_req) {
  //  discuss at: http://phpjs.org/functions/array_rand/
  // original by: Waldo Malqui Silva
  //   example 1: array_rand( ['Kevin'], 1 );
  //   returns 1: 0

  var indexes = [];
  var ticks = num_req || 1;
  var checkDuplicate = function(input, value) {
    var exist = false,
      index = 0,
      il = input.length;
    while (index < il) {
      if (input[index] === value) {
        exist = true;
        break;
      }
      index++;
    }
    return exist;
  };

  if (Object.prototype.toString.call(input) === '[object Array]' && ticks <= input.length) {
    while (true) {
      var rand = Math.floor((Math.random() * input.length));
      if (indexes.length === ticks) {
        break;
      }
      if (!checkDuplicate(indexes, rand)) {
        indexes.push(rand);
      }
    }
  } else {
    indexes = null;
  }

  return ((ticks == 1) ? indexes.join() : indexes);
}