Emulator stops when focus switches away from tab about bbcmicrobot HOT 1 OPEN

There's no code here which runs in the browser - if you're using the editor at https://bbcmic.ro/ that's https://github.com/mattgodbolt/owlet-editor

However, I think it's standard browser behaviour - I think they initially throttle then pause tabs which aren't in the foreground (otherwise sites with badly written javascript or actively nasty cryptomining-type code would consume resources).

If you have a long running BBC BASIC program beebjit is a better approach than jsbeeb (the emulator in owlet) - for example beebjit can usually run 3 hours of emulated time in well under a minute (the speed-up varies as it depends on what's being emulated).

The code here uses beebjit by default, and has a command line "try" mode which runs for 3 hours before taking a screenshot or recording 3 seconds of video which might be what you want or at least a useful starting point - see the rocket and clapper board emojis in the docs.

from bbcmicrobot.