movementY property
The movementY read-only property of the MouseEvent interface
provides the difference in the Y coordinate of the mouse pointer between
the given event and the previous Element.mousemove_event event.
In other words, the value of the property is computed like this:
currentEvent.movementY = currentEvent.screenY - previousEvent.screenY.
Warning: Browsers [use different units for
movementYand MouseEvent.screenY](https://github.com/w3c/pointerlock/issues/42) than what the specification defines. Depending on the browser and operating system, themovementYunits may be a physical pixel, a logical pixel, or a CSS pixel. You may want to avoid the movement properties, and instead calculate the delta between the current client values (MouseEvent.screenX, MouseEvent.screenY) and the previous client values.
Implementation
external double get movementY;