MouseWheel Event Crossbrowser

jquery.mousewheel.example.coffee

# The better is to use the next: https://github.com/jquery/jquery-mousewheel 
$('body').on('mousewheel', onMouseWheel);

onMouseWheel = (e) ->
  scrollDistance = e.deltaY * e.deltaFactor
  wHeight = $(window).innerHeight()
  newScrollTop = scrollDistance * -1 + $('body').scrollTop()

  #Example of use, automatic scrolldown when the next slide is in the middle it scrolls down automatically
  clearTimeout(window._scrollTimer)
  window._scrollTimer = setTimeout(() ->
    currentSlide = getCurrentSlide()
    if scrollDistance * -1 > 0  # Down
      newSlide = getNextSlide(currentSlide)
      if !newSlide
        return
      offset = slidesPosition[newSlide + "Pixels"] 
      if offset < newScrollTop || offset > newScrollTop + wHeight
        return
    animateScroll(offset, 300)
  , 500)
  

getCurrentSlide = () ->
  currentSlide = null
  currentTop = $('body').scrollTop()
  for i in [0...slides.length]
    slide = slides[i]
    slideTop = slidesPosition[slide + "Pixels"] 
    if currentTop == slideTop || (currentTop > slideTop && currentTop < slidesPosition[slides[i+1] + "Pixels"])
      currentSlide = slide
      break
  return if currentSlide then currentSlide else slides[slides.length - 1]


getPreviousSlide = (name) ->
  previousSlide = null
  $slides = $('.slide')  
  for i in [0...$slides.length]
    $slide = $slides.eq(i)
    if $slide.data('name') == name && i > 0
      previousSlide = $slides.eq(i-1).data('name')
      break
  previousSlide

getNextSlide = (name) ->
  nextSlide = null
  $slides = $('.slide')
  for i in [0...$slides.length]
    $slide = $slides.eq(i)
    if $slide.data('name') == name && $slides.length > i+1
      nextSlide = $slides.eq(i+1).data('name')
      break
  nextSlide

mousewheelEvent.coffee

window.getMouseWheelEventName = () ->
  if 'onwheel' in document
    'wheel' 
  else if 'onmousewheel' in document 
    'mousewheel' 
  else 
    'DOMMouseScroll'