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, and is common performance bottleneck.
- elem.offsetLeft,- elem.offsetTop,- elem.offsetWidth,- elem.offsetHeight,- elem.offsetParent
- elem.clientLeft,- elem.clientTop,- elem.clientWidth,- elem.clientHeight
- elem.getClientRects(),- elem.getBoundingClientRect()