Functions flushing browser's "reflow" queue:
offsetTop
,offsetLeft
,offsetWidth
,offsetHeight
scrollTop
/Left
/Width
/Height
clientTop
/Left
/Width
/Height
getComputedStyle()
, orcurrentStyle
in IE
All of these above are essentially requesting style information about a node, and any time you do it, the browser has to give you the most up-to-date value. In order to do so, it needs to apply all scheduled changes, flush the queue, bite the bullet and do the reflow.
References: