Moves an array item from one position in an array to another.

move.js

/* #move - Moves an array item from one position in an array to another.
     Note: This is a pure function so a new array will be returned, instead
     of altering the array argument.
    Arguments:
    1. array     (String) : Array in which to move an item.         (required)
    2. moveIndex (Object) : The index of the item to move.          (required)
    3. toIndex   (Object) : The index to move item at moveIndex to. (required)
  */
function move(array, moveIndex, toIndex) {
  let item = array[moveIndex]
  let length = array.length
  let diff = moveIndex - toIndex

  if (diff > 0) {
    // move left
    return [
      ...array.slice(0, toIndex),
      item,
      ...array.slice(toIndex, moveIndex),
      ...array.slice(moveIndex + 1, length),
    ]
  } else if (diff < 0) {
    // move right
    return [
      ...array.slice(0, moveIndex),
      ...array.slice(moveIndex + 1, toIndex + 1),
      item,
      ...array.slice(toIndex + 1, length),
    ]
  }
  return array
}