ResizeObserver()

The ResizeObserver constructor creates a new ResizeObserver object, which can be used to report changes to the content or border box of an Element or the bounding box of an SVGElement.

Inputs: callback The function called whenever an observed resize occurs. The function is called with two parameters: entries An array of ResizeObserverEntry objects that can be used to access the new dimensions of the element after each change. observer A reference to the ResizeObserver itself, so it will definitely be accessible from inside the callback, should you need it. This could be used for example to automatically unobserve the observer when a certain condition is reached, but you can omit it if you don’t need it.