statu = true

$win = $ window

$doc = $ document

winHeight = $win.height()

docHeight = $doc.height()

​

getIndex = (num)->

  index = 0 ^ num / winHeight

​

toIndex = (index, ms)->

  height = index * winHeight

  ms = ms || 0

  $('html, body').animate scrollTop : height, ms, -> statu = true

​

$win.on 'mousewheel', (event)->

​

  delta = event.originalEvent.wheelDelta or -event.originalEvent.detail

  docScrollTop = $doc.scrollTop()

  index = getIndex(docScrollTop)

​

  if delta <= 0

    index += 1

  else

    index -= 1

​

  if statu == true

    statu = false

    toIndex(index, 500)

​

  event.preventDefault()