Javascript Array filter(callback, scope)

// Array.prototype.filter
Array.prototype.filter = function filter(callback, scope) {
  for (var array = this, arrayB = [], index = 0, length = array.length, element; index < length; ++index) {
    element = array[index];/*from  ww w  .j  av a  2 s  .  c o m*/

    if (callback.call(scope || window, element, index, array)) {
      arrayB.push(element);
    }
  }

  return arrayB;
};