Refs / code to draw from / things to consider

• ContentTranslation code - appears to depend on page visibility api, probably the easiest to implement
• EventLogging code - has some handling for browsers that don't implement the page visibility api
• https://developer.mozilla.org/en-US/docs/Web/API/Page_Visibility_API
• https://www.mediawiki.org/wiki/Template:Compatibility_browser
• https://caniuse.com/pagevisibility

Of the supported browsers, the desktop browsers allow using the pagevisibility api, but the mobile ones don't always

• Safari (MW supports 5.1+, only available in 6.1+)
• iOS (MW supports 6.1+, only available in 7+)
• Android (MW supports 4.1+, only available in 81+ (though the numbering system changed in between))

T229239: Refresh target browser support for MW, dropping less-used browsers from Grade A to Grade C would solve the Safari and iOS support by dropping the versions that don't support the api
Not sure how to handle android

...that being said, this is geared towards desktops, not mobile views, and is not critical, so adding this handling when the page visibility api is available is better than nothing

Event handler should be attached in the "On ready initialization" for SpecialGlobalWatchlist.display.js, and in mounted for the vue version. If the visibility is hidden, and live updates is true, should set to paused, and if it is visible, and live updates is paused, should set it back to true.

Change 643157 had a related patch set uploaded (by DannyS712; owner: DannyS712):
[mediawiki/extensions/GlobalWatchlist@master] Only run live updates while the tab is visible

https://gerrit.wikimedia.org/r/643157

In T268266#6635408, @DannyS712 wrote:

Of the supported browsers, the desktop browsers allow using the pagevisibility api, but the mobile ones don't always

Have you considered using document.hasFocus() instead? It has better support for old mobile browsers, but might be a pain to use as the boolean value would need to be polled periodically (there's no event to listen to).

In T268266#6712028, @SD0001 wrote:

In T268266#6635408, @DannyS712 wrote:

Of the supported browsers, the desktop browsers allow using the pagevisibility api, but the mobile ones don't always

Have you considered using document.hasFocus() instead? It has better support for old mobile browsers, but might be a pain to use as the boolean value would need to be polled periodically (there's no event to listen to).

I think the fact that there is no event rules it out for now, but I'll look into adding that in addition to using the pagevisibility api

Test wiki created on Patch Demo by GDubuc (WMF) using patch(es) linked to this task:

http://patchdemo.wmflabs.org/wikis/234c3863feb3b9a0b8b1c1e0e2223b84/w/

Test wiki created on Patch Demo by GDubuc (WMF) using patch(es) linked to this task:

http://patchdemo.wmflabs.org/wikis/f4d9b5e0597452dab7b4f3c8ae3d2928/w/

Change 643157 merged by jenkins-bot:
[mediawiki/extensions/GlobalWatchlist@master] Only run live updates while the tab is visible

https://gerrit.wikimedia.org/r/643157

Test wiki on Patch Demo by GDubuc (WMF) using patch(es) linked to this task was deleted:

https://patchdemo.wmflabs.org/wikis/234c3863feb3b9a0b8b1c1e0e2223b84/w/

Test wiki on Patch Demo by GDubuc (WMF) using patch(es) linked to this task was deleted:

https://patchdemo.wmflabs.org/wikis/f4d9b5e0597452dab7b4f3c8ae3d2928/w/