offsetX and offsetY give directly the offset which so far was calculated in a multi-step process; these properties of mouse event have a very good support in browsers (see https://caniuse.com/mdn-api_mouseevent_offsetx - 97% coverage).
By delegating this to the browser, you get a better performance and correctness (previous code was not working when dagitty is placed inside an absolutely positioned or scrollable element).
offsetX
andoffsetY
give directly the offset which so far was calculated in a multi-step process; these properties of mouse event have a very good support in browsers (see https://caniuse.com/mdn-api_mouseevent_offsetx - 97% coverage).By delegating this to the browser, you get a better performance and correctness (previous code was not working when dagitty is placed inside an absolutely positioned or scrollable element).