各种笔记 – The `wheel` Event Across Browsers and OS's - the-dissidents/subtle GitHub Wiki

Trackpad pinching

macOS / Safari

X = deltaY (floating point), Y = wheelDeltaY

$Y = \text{trunc}(-3X)$

macOS / Chrome

deltaY looks like the same as Safari.

wheelDeltaY is always ±120.

Windows / Edge

No data yet (remote controller doesn't support trackpad pinching)

Trackpad scrolling

macOS / Safari

X = delta* (integer), Y = wheelDelta*

$Y = \text{trunc}(-3X)$

macOS / Chrome

The same

Windows / Edge

X = delta*, Y = wheelDelta* (integer)

$X = Y / -1.2$

Mouse wheel scrolling

macOS / Safari

deltaY is always ±120, for one wheel step (positive = down)

wheelDeltaY is deltaY * -3.

macOS / Chrome

The same

Windows / Edge

deltaY is always ±100, for one wheel step (positive = down)

wheelDeltaY is deltaY * -1.2.

Summary

delta*

Environment	Pinch	Trackpad scroll	Mouse scroll
macOS/Safari	float	integer	±120
macOS/Chrome	float	integer	±120
Windows/Edge	N/A	multiple of $5/6$	±100

wheelDelta*

Environment	Pinch	Trackpad scroll	Mouse scroll
macOS/Safari	trunc(-3*delta*)	trunc(-3*delta*)	-3*delta*
macOS/Chrome	±120	trunc(-3*delta*)	-3*delta*
Windows/Edge	N/A	-1.2*delta*	-1.2*delta*