How to get an element's top position relative to the browser's viewport?

Question

I want to get the position of an element relative to the browser\'s viewport (the viewport in which the page is displayed, not the whole page). How can this be done in JavaS

Answer 1

Thanks for all the answers. It seems Prototype already has a function that does this (the page() function). By viewing the source code of the function, I found that it first calculates the element offset position relative to the page (i.e. the document top), then subtracts the scrollTop from that. See the source code of prototype for more details.