如何检查使用jQuery滚动了多少元素？

Question

Google Reader and Gmail have scrollable divs that has a shadow on top if the div was scrolled. The shadow changes opacity depending on how much the div was scrolled. How can I check how much an element was scrolled using Javascript/jQuery?

Answer 1

http://api.jquery.com/scrollLeft

http://api.jquery.com/scrollTop

or

http://api.jquery.com/scroll

Answer 2

Use $(el).scrollTop() to find how many pixels from the top an element (including, say, body ) has been scrolled.

As @nathanjosiah suggests, check the docs for details.