Array prototype partition

gistfile1.txt

/**
 * Partition an array on the result of a boolean test
 * @return {Array[Array]} where the first array contains the element that passed the test
 */
Array.prototype.partition = (test) => this.reduce(
  (accumulator, val) => {
    accumulator[test(val)?0:1] = val
    return accumulator
  })([[], []])
}