Offsetparent is a read-only property that returns a reference to the container element that recently displayed the specified location. If the element does not have a location specified, the nearest element or root element (in standard mode, HTML, or body in weird mode) is offsetparent. When the element style.display= ' None ', offsetparent returns NULL. Because offsettop and offsetleft are relative to the margins, offsetparent is very useful.
Browser Compatibility on a WebKit-centric browser, NULL is returned if the element is hidden (the element or ancestor element style.display= ' none ') or the element itself style.position= ' fixed '. on IE (9), as the element style.position= ' fixed ', the property returns NULL. (however Display:none does not affect this browser)
<! DOCTYPE html>
https://developer.mozilla.org/en-US/docs/Web/API/HTMLElement.offsetParent
