jscrollTo - scroll page to bring element into view

jscrollTo.js.coffee

$ = jQuery

$window = $(window)

methods =
  init: (options = {}) ->
    return this.each () ->
      $this = $(this)
      offset = $this.offset()
      x = undefined
      y = undefined
      st = $window.scrollTop()
      sl = $window.scrollLeft()
      if ( offset.left ) < sl
        x = if offset.left - 20 < 0  then 0 else offset.left - 20
      else if offset.left + $this.outerWidth()  > ( sl + $window.width() + 1 )
        x = offset.left - 20
      if ( offset.top - 150 ) < st
        y = offset.top - 150
      else if (offset.top + $this.outerHeight()) + 50 > (st + $window.height())
        y =  50 + offset.top + $this.outerHeight() - $window.height()
      if x? or y?
        x ?= 0
        y ?= 0
        scrollTo x, y


$.fn.jscrollTo = (method) ->
  if methods[method]?
    return methods[method].apply( this, Array.prototype.slice.call( arguments, 1 ))
  else if typeof method == 'object' or ! method
    return methods.init.apply( this, arguments )
  else
    $.error( 'Method ' +  method + ' does not exist on jQuery.jscrollTo' )