Alarms API로 작업 예약하기

In Manifest V3 the service worker unloads when idle, so setTimeout and setInterval are unreliable for scheduled work. The alarms API survives this by waking the worker when it is time to run.

Add the alarms permission to the manifest before using the API.

Use alarms.create with delayInMinutes for a single delayed task.

Add periodInMinutes to make the alarm fire again and again on a schedule.

Listen for onAlarm at the top level of your service worker. The alarm object tells you which one fired.

Because the worker restarts, register onAlarm synchronously when the script first runs, not inside an async callback, or the wake-up may be missed.

For packed extensions the smallest repeating period is about one minute. Shorter intervals are clamped, so do not rely on second-level timing.

Use alarms.get or alarms.getAll to check what is scheduled, useful for avoiding duplicates.

Remove a single alarm with clear or all of them with clearAll when a feature is turned off.

Set up your alarms in the onInstalled event so they exist from the moment the extension is installed or updated.

The worker may unload soon after the alarm. Keep the task quick, persist state to storage, and avoid long-running loops that could be cut off.

You learned reliable scheduling:

• Use alarms.create with delay or period
• Handle onAlarm registered at the top level
• Respect the ~1 minute minimum period
• Inspect, clear, and recreate alarms
• Keep alarm work short

The alarms API makes background scheduling dependable under Manifest V3.