43       , position = this.$element.offset()
44       , offset = this.options.offset
45       , offsetBottom = offset.bottom
46       , offsetTop = offset.top
50     if (typeof offset != 'object') offsetBottom = offsetTop = offset
51     if (typeof offsetTop == 'function') offsetTop = offset.top()
52     if (typeof offsetBottom == 'function') offsetBottom = offset.bottom()
86     offset: 0  property in $.fn.affix.defaults
107       data.offset = data.offset || {}
109       data.offsetBottom && (data.offset.bottom = data.offsetBottom)
110       data.offsetTop && (data.offset.top = data.offsetTop)