Shuffle array function.

shuffle-array.js

function shuffleArray (array) {
  let currentIndex = array.length
  let temporaryValue
  let randomIndex

  // While there remain elements to shuffle.
  while (currentIndex !== 0) {
    // Pick a remaining element
    randomIndex = Math.floor(Math.random() * currentIndex)
    currentIndex -= 1

    // And swap it with the current element.
    temporaryValue = array[currentIndex]
    array[currentIndex] = array[randomIndex]
    array[randomIndex] = temporaryValue
  }

  return array
}