Coffeescript Binary Search (By Ryan Shaw)

gistfile1.coffee

binaryFindClosest = (haystack, needle) ->
  closestBelow = 0
  closestAbove = haystack.length - 1
  middle       = Math.floor (closestBelow + closestAbove) / 2

  while haystack[middle] isnt needle and closestBelow < closestAbove
    if  needle < haystack[middle]
      closestAbove = middle - 1
    else if needle > haystack[middle]
      closestBelow = middle + 1
   
    # recalculate middle
    middle = Math.floor (closestAbove + closestBelow) / 2

  deltaBelow = needle - closestBelow
  deltaAbove = closestAbove - needle
  if deltaBelow < deltaAbove
    return direction: 'down', value: closestBelow, delta: deltaBelow
  else
    return direction: 'up', value: closestAbove, delta: deltaAbove