Javascript: Does modifying scrollTop/scrollLeft trigger browser reflow?

Question

I'm wondering if animating the scrollbars with Javascript triggers browser reflow.

Any difference across different browser implementations?

window.pageXOffset & window.pageYOffset
document.documentElement.scrollLeft & document.documentElement.scrollTop
document.body.scrollLeft & document.body.scrollTop

Thanks!

score 12 · Accepted Answer · answered Mar 10 '10 at 23:57

12

I dug in deeper and found this link which says it does cause reflow: http://www.phpied.com/rendering-repaint-reflowrelayout-restyle/

I also tested it and modifying scrollTop and scrollLeft both trigger reflow (in Firefox at least).

Heh sorry for answering my own question, but hopefully this info is useful for someone :).

answered Mar 10 '10 at 23:57

Jon Raasch

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Nice article, thanks. And sorry I was too hasty to answer this question without thorough research. – Marcel Korpel Mar 11 '10 at 12:18
yes, triggers reflow, according to my test and the comprehensive list from Paul Irish: https://gist.github.com/paulirish/5d52fb081b3570c81e3a – HolgerJeromin Jun 05 '19 at 13:50

score 1 · Answer 2 · edited May 23 '17 at 12:06

1

According to this question, no.

edited May 23 '17 at 12:06

Community

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answered Mar 10 '10 at 00:33

Marcel Korpel

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Javascript: Does modifying scrollTop/scrollLeft trigger browser reflow?

2 Answers2