MV3 Content Script Limits..

[Sonny Chee]

Hey Guys,

My understanding is that under MV3, content scripts (unlike the background service worker) can run for however long they want.  I didn't see any specific changes to them in migrating from mv2 to mv3...

[wOxxOm]

The "isolated world" where the content scripts run doesn't mean they are separate from the page. Content scripts run in the page as an integral part of the page, just like any other page script, so it's impossible to pause them separately from the page. They run as long as the page itself.

[Sonny Chee]

When you say: 

"They run as long as the page itself."



Does that mean, they run as long as the tab is open? More concretely, if I have setTimeout( function, 10*60*1000 ), can I be certain that the function will be execute in 10 minutes?

[hrg...@gmail.com]

 

can I be certain that the function will be execute in 10 minutes?

You can't be certain because:

1. A tab can navigate to another page, causing your content script to be unloaded
   
2. A tab can be automatically discarded  by the browser if it needs to release RAM
   
3. A tab that hasn't been visible for more than 5 minutes will be throttled down and setTimeout will run at most once per minute.
   

More info here: https://docs.google.com/document/d/11FhKHRcABGS4SWPFGwoL6g0ALMqrFKapCk5ZTKKupEk/view

 

[wOxxOm]

The page can also clear your timer intentionally or accidentally because timers aren't isolated, so it's more reliable to use chrome.alarms API in the background script  and send a message to the content script when the alarm goes off.