Feature detect request: Web App Manifest (PWA Support)

[benseven]

Looking to be able to combine feature detection for service workers — already in Modernizr — with a test for whether the browser supports / cares about the Web App Manifest, so as to progressively disclose the existence of PWA features to the user.

Example: A user on the 'my account' page of a membership portal who is on iOS 11.3 or later sees a promotion block about our new virtual membership card added to their home screen as a standalone PWA, but a user on iOS 11.2 or earlier - which does not support basic PWA features - does not see the promotion block for something their browser doesn't support.

Thanks!

[roblarsen]

Looking at the spec, would:

Modernizr.addTest("webappmanifest","BeforeInstallPromptEvent" in window)

work?

If so, that's like 50% of an easy PR for someone right there.

[benseven]

Thanks for the help!

I've started a Codepen tracking my aims and tests - unfortunately as you'll see from the results there, testing this pen based on your suggestion resulted in a false negative from Safari on iOS 11.3 - according to this tweet from a Safari engineer, Web App Manifest is supported there.

I'm assuming this is because while Safari on iOS 11.3 will consult the web app manifest, it doesn't support BeforeInstallPromptEvent.

Potentially, I could combine that first test (BeforeInstallPromptEvent) with a check for Service Worker support (already in Modernizr) and some kind of horrible test specifically for Safari on iOS 11.3 and later, but if you have any nicer ideas I'd love to hear them.

[NOtherDev]

It is problematic to use BeforeInstallPromptEvent as the only check. Lack of existence of such does not indicate the lack of "add to home screen" support nor lack of Web Manifest support.

Technically, to detect just the manifest support in any form (including the most basic ones), one should check if <link> tag supports the rel="manifest" value.

See the whole discussion here: NOtherDev/whatwebcando#36.