Nice nav & scrolling

gistfile1.coffee

$ () ->
  scrolls = $('.scroll')
  if scrolls.length
    scrolls.click (e) ->
      href = $(this).attr('href')
      fragments = href.split('#')
      if fragments.length > 1 && fragments[0] == "#{window.location}".split('#')[0]
        e.preventDefault()
        $('html,body').animate({scrollTop: $("a[name=#{fragments[fragments.length-1]}]").offset().top}, {duration: 'fast', complete: () ->
          window.location = href
        })
    scrolled = false
    $(window).scroll () ->
      scrolled = true
    setInterval( () ->
      return unless scrolled
      scrolled = false
      top = $(window).scrollTop()
      return unless top > 0
      rev_scrolls = scrolls.get().reverse()
      if $(document).height() == (top + $(window).height())
        anchor = $(rev_scrolls[0])
        unless anchor.parent('li').hasClass('selected')
          anchor.parent('li').addClass('selected')
          if window.history && window.history.replaceState
            window.history.replaceState({}, null, anchor.attr('href'))
        $(rev_scrolls).each (i) ->
          if i > 0
            $(this).parent('li').removeClass('selected')
      else
        used = false
        $(rev_scrolls).each () ->
          anchor = $(this)
          fragments = anchor.attr('href').split('#')
          if fragments.length > 1
            if !used && (top+10) > ($("a[name=#{fragments[fragments.length-1]}]").offset().top)
              unless anchor.parent('li').hasClass('selected')
                anchor.parent('li').addClass('selected')  
                if window.history && window.history.replaceState
                  window.history.replaceState({}, null, anchor.attr('href'))
              used = true
            else
              anchor.parent('li').removeClass('selected')
    , 200)