CoffeeScript - detect if current scroll position is below div

问题

I would like to detect when the user scrolls past a certain point in the window.

[Meta]
X
scroll below = alert() 

I'm quite new to CoffeeScript, so any help would be great!

What I currently have is this:

$("#area_1").bind('scroll', ->
  scrollPosition = $(this).scrollTop() + $(this).outerHeight()
  divTotalHeight = $(this)[0].scrollHeight()
  if (scrollPosition >= divTotalHeight)
    alert('end reached')
  )

And no alert is showing up. Any tips?

Update I suspect that my problem have to do with my two variables. Here is an example:

$("#area_1").bind($(window).scroll ->
  alert('before 1') # Gets called
  scrollPosition = $(this).scrollTop() + $(this).outerHeight()
  divTotalHeight = $(this)[0].scrollHeight()
  alert('before 2') # Never gets called
  if (1 == 1)
    alert('should get called but dosn't')
)

来源：https://stackoverflow.com/questions/18292183/coffeescript-detect-if-current-scroll-position-is-below-div