How to get and set the current web page scroll position?

You're looking for the document.documentElement.scrollTop property.

Update 2021: browsers inconsistencies with scrollTop seem to have disappeared.

There are some inconsistencies in how browsers expose the current window scrolling coordinates. Google Chrome on Mac and iOS seems to always return 0 when using document.documentElement.scrollTop or jQuery's $(window).scrollTop().

However, it works consistently with:

// horizontal scrolling amount
window.pageXOffset

// vertical scrolling amount
window.pageYOffset

The currently accepted answer is incorrect - document.documentElement.scrollTop always returns 0 on Chrome. This is because WebKit uses body for keeping track of scrolling, whereas Firefox and IE use html.

To get the current position, you want:

document.documentElement.scrollTop || document.body.scrollTop

You can set the current position to 1000px down the page like so:

document.documentElement.scrollTop = document.body.scrollTop = 1000;

Or, using jQuery (animate it while you're at it!):

$("html, body").animate({ scrollTop: "1000px" });