Why were window.scrollY and window.scrollX introduced?

Question

As far as I know, pageY_/XOffset properties were already available since Netscape 4 era.
And it seems scrollY_/X were introduced circa Netscape 6.

Alternative question: Is there a browser which implements scrollY_/X but doesn't support pageY_/XOffset?

Answer 1

Everything about it. As you can see pageXOffset isn't supported by Internet Explorer. In IE you should use scrollLeft / scrollTop of document.body or document.documentElement depending what works (just like it is implemented in jQuery).

You can check it here: http://jsfiddle.net/8RFAn/1/

And I don't know why window.scrollX/Y were introduced, for me these properties looks like pageX/YOffset in terms of effect and browsers in which are implemented.