code: function filterArray(fn, array) {
    let filteredItems = [],
        index = -1;
  
    while (++index < array.length) {
      if (fn(array[index], index, array)) {
        filteredItems[filteredItems.length] = array[index];
      }
    }
  
    return filteredItems;
  }
docs: @function filterArray
  
  @description
  filter down the items to those that return truthy based on the call of fn
  
  @param {function(*, (number|string), Array<*>): *} fn the method to filter with
  @param {Array<*>} array the array of items to filter
  @returns {Array<*>} the filtered items