How to implement an onmousedown and onmouseup on an iPhone touch screen
Solution 1:
The equivalent for onmousedown on touchscreen devices is ontouchstart, and the equivalent of onmouseup is ontouchend.
If you would also like to detect dragging, you could use ontouchmove which is fired every time you move your finger after touching the screen.
Solution 2:
You might be interested in onpointerup and onpointerdown events which will work on both touch and non touch devices. Check browser support