Welcome What's new in Chrome extensions Getting started API Reference Samples
Welcome What's new in Chrome extensions Getting started API Reference Samples

chrome.alarms

  • Description

    Use the chrome.alarms API to schedule code to run periodically or at a specified time in the future.

  • Permissions
    alarms

Summary

Types

Alarm

Properties

  • name

    string

    Name of this alarm.

  • periodInMinutes

    number optional

    If not null, the alarm is a repeating alarm and will fire again in periodInMinutes minutes.

  • scheduledTime

    number

    Time at which this alarm was scheduled to fire, in milliseconds past the epoch (e.g. Date.now() + n). For performance reasons, the alarm may have been delayed an arbitrary amount beyond this.

AlarmCreateInfo

Properties

  • delayInMinutes

    number optional

    Length of time in minutes after which the onAlarm event should fire.

  • periodInMinutes

    number optional

    If set, the onAlarm event should fire every periodInMinutes minutes after the initial event specified by when or delayInMinutes. If not set, the alarm will only fire once.

  • when

    number optional

    Time at which the alarm should fire, in milliseconds past the epoch (e.g. Date.now() + n).

Methods

clear

chrome.alarms.clear(
  name?: string,
  callback?: function,
)
Promise

Clears the alarm with the given name.

Parameters

  • name

    string optional

    The name of the alarm to clear. Defaults to the empty string.

  • callback

    function optional

    The callback parameter looks like: (wasCleared: boolean) => void

    • wasCleared

      boolean

Returns

  • Promise<boolean>

    Pending

    This only returns a Promise when the callback parameter is not specified, and with MV3+. The type inside the Promise is the same as the 1st argument to callback.

clearAll

chrome.alarms.clearAll(
  callback?: function,
)
Promise

Clears all alarms.

Parameters

  • callback

    function optional

    The callback parameter looks like: (wasCleared: boolean) => void

    • wasCleared

      boolean

Returns

  • Promise<boolean>

    Pending

    This only returns a Promise when the callback parameter is not specified, and with MV3+. The type inside the Promise is the same as the 1st argument to callback.

create

chrome.alarms.create(
  name?: string,
  alarmInfo: AlarmCreateInfo,
)

Creates an alarm. Near the time(s) specified by alarmInfo, the onAlarm event is fired. If there is another alarm with the same name (or no name if none is specified), it will be cancelled and replaced by this alarm.

In order to reduce the load on the user's machine, Chrome limits alarms to at most once every 1 minute but may delay them an arbitrary amount more. That is, setting delayInMinutes or periodInMinutes to less than 1 will not be honored and will cause a warning. when can be set to less than 1 minute after "now" without warning but won't actually cause the alarm to fire for at least 1 minute.

To help you debug your app or extension, when you've loaded it unpacked, there's no limit to how often the alarm can fire.

Parameters

  • name

    string optional

    Optional name to identify this alarm. Defaults to the empty string.

  • Describes when the alarm should fire. The initial time must be specified by either when or delayInMinutes (but not both). If periodInMinutes is set, the alarm will repeat every periodInMinutes minutes after the initial event. If neither when or delayInMinutes is set for a repeating alarm, periodInMinutes is used as the default for delayInMinutes.

get

chrome.alarms.get(
  name?: string,
  callback?: function,
)
Promise

Retrieves details about the specified alarm.

Parameters

  • name

    string optional

    The name of the alarm to get. Defaults to the empty string.

  • callback

    function optional

    The callback parameter looks like: (alarm?: Alarm) => void

Returns

  • Promise<Alarm | undefined>

    Pending

    This only returns a Promise when the callback parameter is not specified, and with MV3+. The type inside the Promise is the same as the 1st argument to callback.

getAll

chrome.alarms.getAll(
  callback?: function,
)
Promise

Gets an array of all the alarms.

Parameters

  • callback

    function optional

    The callback parameter looks like: (alarms: Alarm[]) => void

Returns

  • Promise<Alarm[]>

    Pending

    This only returns a Promise when the callback parameter is not specified, and with MV3+. The type inside the Promise is the same as the 1st argument to callback.

Events

onAlarm

chrome.alarms.onAlarm.addListener(
  callback: function,
)

Fired when an alarm has elapsed. Useful for event pages.

Parameters

  • callback

    function

    The callback parameter looks like: (alarm: Alarm) => void

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