Framework: hasTouch() considered harmful

[nylen]

We have a "touch detect" library and use it in a few places. I've used it before, but I won't be anymore, and I recommend that we remove it entirely.

It's not really possible to reliably detect a touch device. You can detect the touch events APIs, but browsers have a history of implementing and activating these APIs on devices that would be considered "non-touch".

Also, there are lots of "hybrid" devices like the Surface family and other laptops that support both touch and mouse/keyboard as methods of interaction. The user can dynamically change between these methods, which is not possible to detect ahead of time.

For a longer, but excellent, writeup: You Can't Detect a Touchscreen

Modernizr (where we originally got our touchDetect code) has since changed the name of this check from Modernizr.touch to Modernizr.touchevents, and added a ton of warnings about its use: Modernizr/Modernizr#548, feature-detects/touchevents.js.

Similarly, our own library code says:

[This test] may not accurately detect a touch screen, but may be close enough depending on the use case.

Finally, we've had multiple issues with this in the past. To start:

• 11908-gh-calypso-pre-oss - we decided to move away from hasTouch for the media modal
• 11922-gh-calypso-pre-oss - same for the editor permalink control
• Editor: Remove Touchdetect Logic From Pinning Toolbar #1435 / Editor: Disable Toolbar Pin on isMobile not hasTouch #1452 - same for toolbar pinning

[lancewillett]

Hi @nylen — cleaning up older issues in a bug scrub. Did this get traction? Do you want more opinions or discussion? If not, we'd like to close it.

[nylen]

I don't think this should be closed - it's an outstanding issue with the current codebase.

[lancewillett]

Who's going to work on it? Can we add it to a milestone? CC @mtias

The problem with just leaving it is it'll be stale very quickly and never get addressed.

[lancewillett]

No action in 5 months still. Will close at next bug scrub if it's not addressed.

[johnHackworth]

This is very much a still standing issue 👍
#9977 (comment)

[tyxla]

I've opened an issue for #9977 (comment): #9981

[alisterscott]

Closing as #9981 is fixed