What forces layout/reflow. The comprehensive list.
# What forces layout / reflow All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or [layout thrashing](http://www.kellegous.com/j/2013/01/26/layout-performance/), and is common performance bottleneck. Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details. ### Element APIs ##### Getting box metrics * `elem.offsetLeft`, `elem.offsetTop`, `elem.offsetWidth`, `elem.offsetHeight`, `elem.offsetParent` * `elem.clientLeft`, `elem.clientTop`, `elem.clientWidth`, `elem.clientHeight` * `elem.getClientRects()`, `elem.getBoundingClientRect()`