In the DOM, what is the difference between an element’s offsetHeight and its scrollHeight? An image in explanation would be a great help.
HTMLElement.offsetHeight is a measurement which includes the element borders, the element vertical padding, the element horizontal scrollbar (if present, if rendered) and the element CSS height.
HTMLElement.scrollHeight is a measurement of the height of an element's content including content not visible on the screen due to overflow. The value returned by HTMLElement.scrollHeight WILL include the padding-top and padding-bottom, but will NOT include the element borders or the element horizontal scrollbar.
This page and this page are my sources.
The MDN documentation also provides images to demonstrate.