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Creates a new alarm.


  name,              // optional string
  alarmInfo          // optional object


string. A name for the alarm. Defaults to the empty string.
This can be used to refer to a particular alarm in alarms.get() and alarms.clear(). It will also be available in alarms.onAlarm as the name property of the alarms.Alarm object passed into the listener function.
Alarm names are always unique (within the scope of a single add-on). If the name given here matches the name of an existing alarm created by this add-on, then the existing alarm is removed and won't fire.

object. You can use this to specify when the alarm will initially fire, either as an absolute value (when), or as a delay from the time the alarm is set (delayInMinutes). To make the alarm recur, specify periodInMinutes.

On Chrome, unless the add-on is loaded unpackaged, alarms it creates are not allowed to fire more than once per minute. If an add-on tries to set delayInMinutes to a value < 1, or when to a value < 1 minute in the future, then the alarm will fire after 1 minute. If an add-on tries to set periodInMinutes to a value < 1, then the alarm will fire every minute.

The alarmInfo object may contain the following properties:

double. The time the alarm will fire first, given as milliseconds since the epoch. To get the number of milliseconds between the epoch and the current time, use If you specify when, don't specify delayInMinutes.
double. The time the alarm will fire first, given as minutes from the time the alarm is set. If you specify delayInMinutes, don't specify when.
double. If this is specified, the alarm will fire again every periodInMinutes after its initial firing. If you specify this value you may omit both when and delayInMinutes, and the alarm will then fire initially after periodInMinutes. If periodInMinutes is not specified, the alarm will only fire once.

Browser compatibility

ChromeEdgeFirefoxFirefox for AndroidOpera
Basic supportYesNo4548Yes


Create a one-time delay-based alarm with "" for the name:

const delayInMinutes = 5;


Create a periodic delay-based alarm named "my-periodic-alarm":

const delayInMinutes = 5;
const periodInMinutes = 2;

browser.alarms.create("my-periodic-alarm", {

Create a periodic absolute alarm named "my-periodic-alarm":

const when = 1545696000;
const periodInMinutes = 2;

browser.alarms.create("my-periodic-alarm", {

This API is based on Chromium's chrome.alarms API.

Microsoft Edge compatibility data is supplied by Microsoft Corporation and is included here under the Creative Commons Attribution 3.0 United States License.

Document Tags and Contributors

 Contributors to this page: wbamberg, Makyen
 Last updated by: wbamberg,