The Geolocation API provides access to geographical location information associated with the hosting device.

The Devices and Sensors Working Group is updating this specification in the hope of making it a "living standard". As such, we've dropped the "Editions" and aim to continue publishing updated W3C Recommendations of this specification as we add new features or fix bugs.

Introduction

The Geolocation API defines a high-level interface to location information associated only with the device hosting the implementation. Common sources of location information include Global Positioning System (GPS) and location inferred from network signals such as IP address, RFID, WiFi and Bluetooth MAC addresses, and GSM/CDMA cell IDs, as well as user input. The API itself is agnostic of the underlying location information sources, and no guarantee is given that the API returns the device's actual location.

If an end user [=check permission|grants permission=], the Geolocation API:

Scope

This specification is limited to providing a scripting API for retrieving geographic position information associated with a hosting device. The geographic position information is provided in terms of World Geodetic System coordinates [[WGS84]]. It does not include providing a markup language of any kind, nor does not include defining a new URL scheme for building URLs that identify geographic locations.

Changes since last publication

Since publication of the Second Edition in 2016, this specification has received the following changes:

See the commit history for a complete list of changes.

Examples

The API is designed to enable both "one-shot" position requests and repeated position updates. The following examples illustrate common use cases.

Get current position

Request the user's current location. If the user allows it, you will get back a position object.

Watch a position

Request the ability to watch user's current location. If the user allows it, you will get back continuous updates of the user's position.

Stop watching a position

Stop watching for position changes by calling the {{Geolocation/clearWatch()}} method.

Handling errors

When an error occur, the second argument of the {{Geolocation/watchPosition()}} or {{Geolocation/getCurrentPosition()}} method gets called with a {{GeolocationPositionError}} error, which can help you figure out what might have gone wrong.

Using `maximumAge` as cache control

By default, the API always attempts to return a cached position so long as it has a previously acquired position. In this example, we accept a position whose age is no greater than 10 minutes. If the user agent does not have a fresh enough cached position object, it automatically acquires a new position.

Using `timeout`

If you require location information in a time sensitive manner, you can use the {{PositionOptions}} {{PositionOptions/timeout}} member to limit the amount of time you are willing to wait to [=acquire a position=].

Enabling the API in third-party contexts

The default allowlist of `["self"]` allows Geolocation API usage in same-origin nested frames but prevents third-party content from using the API.

Third-party usage can be selectively enabled by adding [^iframe/allow^]`="geolocation"` attribute to an [^iframe^] element:

Alternatively, the API can be disabled in a first-party context by specifying the a HTTP response header:

See [[[permissions-policy]]] for more details about the `Permissions-Policy` HTTP header.

Privacy and security considerations

The API defined in this specification is used to retrieve the geographic location of a hosting device. In almost all cases, this information also discloses the location of the user of the device, thereby potentially compromising the user's privacy.

Privacy considerations for recipients of location information

This section applies to "recipients", which generally means developers utilizing the Geolocation API. Although it's impossible for user agent, or this specification, to enforce these requirements, developers need to read this section carefully and do their best to adhere to the suggestions below. Developers need to be aware that there might be privacy laws in their jurisdictions that can govern the usage and access to users' location data.

Recipients ought to only request position information when necessary, and only use the location information for the task for which it was provided to them. Recipients ought to dispose of location information once that task is completed, unless expressly permitted to retain it by the user. Recipients need to also take measures to protect this information against unauthorized access. If location information is stored, users need to be allowed to update and delete this information.

The recipient of location information need to refrain from retransmitting the location information without the user’s express permission. Care needs to be taken when retransmitting and the use of encryption is encouraged.

Recipients ought to clearly and conspicuously disclose the fact that they are collecting location data, the purpose for the collection, how long the data is retained, how the data is secured, how the data is shared if it is shared, how users can access, update and delete the data, and any other choices that users have with respect to the data. This disclosure needs to include an explanation of any exceptions to the guidelines listed above.

Implementation considerations

Implementers are advised to consider the following aspects that can negatively affect the privacy of their users: in certain cases, users can inadvertently grant permission to the user agent to disclose their location to websites. In other cases, the content hosted at a certain URL changes in such a way that the previously granted location permissions no longer apply as far as the user is concerned. Or the users might simply change their minds.

Predicting or preventing these situations is inherently difficult. Mitigation and in-depth defensive measures are an implementation responsibility and not prescribed by this specification. However, in designing these measures, implementers are advised to enable user awareness of location sharing, and to provide access to user interfaces that enable revocation of permissions.

`Geolocation` interface and callbacks 

        [Exposed=Window]
        interface Geolocation {
          undefined getCurrentPosition (
            PositionCallback successCallback,
            optional PositionErrorCallback? errorCallback = null,
            optional PositionOptions options = {}
          );

          long watchPosition (
            PositionCallback successCallback,
            optional PositionErrorCallback? errorCallback = null,
            optional PositionOptions options = {}
          );

          undefined clearWatch (long watchId);
        };

        callback PositionCallback = undefined (
          GeolocationPosition position
        );

        callback PositionErrorCallback = undefined (
          GeolocationPositionError positionError
        );

Internal slots

Instances of {{Geolocation}} are created with the internal slots in the following table:

Internal slot Description
[[\cachedPosition]] A {{GeolocationPosition}}, initialized to null. It's a reference to the last acquired position and serves as a cache. A user agent MAY evict {{Geolocation/[[cachedPosition]]}} by resetting it to null at any time for any reason.
[[\watchTasks]] Initialized as an empty [=set=] of {{unsigned long}} [=set/item|items=], which represent the identifier for timed [=task=].

`getCurrentPosition()` method

When getCurrentPosition() is invoked, the user agent MUST:

  1. [=Request position=], passing |successCallback|, |errorCallback|, |options|, and (repeats) false.
  2. Return `undefined`.

`watchPosition()` method

When watchPosition() is invoked, the user agent MUST:

  1. Let |watchId:long| be [=request position=], passing |successCallback|, |errorCallback|, |options|, and (repeats) true.
  2. Return |watchId|.

`clearWatch()` method

When clearWatch() is invoked, the user agent MUST:

  1. If [=this=]'s {{Geolocation/[[watchTasks]]}}[|watchId|] [=map/exists=], [=map/remove=] [=this=]'s {{Geolocation/[[watchTasks]]}}[|watchId|].

Request position

Request position by passing a {{PositionCallback}} |successCallback:PositionCallback|, a {{PositionErrorCallback}}`?` |errorCallback:PositionErrorCallback|, {{PositionOptions}} |options:PositionOptions|, a {{boolean}} |repeats:boolean|, and optionally (and only if |repeats| is true) a |previous id:long|.

  1. Let |watchTasks:Set| be [=this=]'s {{Geolocation/[[watchTasks]]}}.
  2. Acquire a watch id.
    1. If |previous id| was provided, let |watchId:long| be |previous id|; Otherwise, let |watchId| be an [=implementation-defined=] {{long}} that is greater than or equal to zero.
    2. [=Set/Append=] |watchId| to |watchTasks|.
    3. Return |watchId| and continue [=in parallel=].
  3. Do security check.
    1. If the environment settings object is a non-secure context, then:
      1. [=Call back with error=] |errorCallback| and {{GeolocationPositionError/PERMISSION_DENIED}}.
      2. [=List/Remove=] |watchId| from |watchTasks|.
      3. Terminate this algorithm.
  4. Wait for document to become visible.
    1. Let |document:Document| be the [=current settings object=]'s [=associated Document=].
    2. If |document:Document| is [=Document/hidden=], wait for the |document| to become [=Document/visible=].
  5. [=Check permission=] passing |errorCallback|. If the check return failure:
    1. [=List/Remove=] |watchId| from |watchTasks|.
    2. Terminate this algorithm.
  6. Acquire position.
    1. Let |acquisitionTime:DOMTimeStamp| be a new {{DOMTimeStamp}} that represents now in milliseconds, using 01 January, 1970 UTC as the epoch.
    2. If |options|.{{PositionOptions/maximumAge}} is greater than 0, and |cachedPosition| is not null:
      1. Let |cachedPosition:GeolocationPosition| be [=this=]'s {{Geolocation/[[cachedPosition]]}}.
      2. Let |cacheTime:long| be |acquisitionTime| minus the value of |options|.{{PositionOptions/maximumAge}} member.
      3. If |cachedPosition|'s {{GeolocationPosition/timestamp}}'s value is greater than |cacheTime|, and |cachedPosition|.{{GeolocationPosition/[[isHighAccuracy]]}} equals |options|.{{PositionOptions/enableHighAccuracy}}:
        1. [=Queue a microtask=] to invoke |successCallback| with |cachedPosition|.
        2. Go to determine repetition steps below.
    3. Let |timeout:Task| be a new timed [=task=] that runs in |options|.{{PositionOptions/timeout}} milliseconds after |acquisitionTime|, which performs the following sub-steps:
      1. If the entry for |timerId| in the [=list of active timers=] has been cleared, then abort these steps.
      2. [=Call back with error=] with |errorCallback| and {{GeolocationPositionError/TIMEOUT}}.
    4. Let |timerId| be an [=implementation-defined=] identifier that represents |timeout|.
    5. Add |timerId| to the [=list of active timers=].
    6. Try to acquire the device's position, optionally taking into consideration the value of |options|.{{PositionOptions/enableHighAccuracy}}:
      1. If acquiring a position succeeds:
        1. Let |position:GeolocationPosition| be [=a new `GeolocationPosition`=] passing |acquisitionTime| and |options|.{{PositionOptions/enableHighAccuracy}}.
        2. Set [=this=]'s {{Geolocation/[[cachedPosition]]}} to |position|.
        3. [=Queue a microtask=] to [=invoke=] |successCallback| with |position|.
      2. If acquiring a position fails:
        1. [=Call back with error=] passing |errorCallback| and {{GeolocationPositionError/POSITION_UNAVAILABLE}}.
    7. Clear |timerId| from the [=list of active timers=].
  7. Determine repetition.
    1. If |repeats| is false:
      1. [=List/Remove=] |watchId| from |watchTasks|.
      2. Terminate this algorithm.
  8. Wait for a significant change of geographic position. What constitutes a significant change of geographic position is left to the implementation. A user agents MAY impose a rate limit on the frequency position changes.
  9. If |watchTasks| [=list/contain|contains=] |watchId|, then:
    1. [=Request position=] passing |successCallback|, |errorCallback|, |options|, |repeats|, and |watchId|.

Check permission

When instructed to check permission, given an {{PositionErrorCallback}}`?` |errorCallback:PositionErrorCallback|:

  1. Let |permission:PermissionState| be [=request permission to use=] "geolocation".
  2. If |permission| is {{PermissionState/"denied"}}, then:
    1. [=Call back with error=] |errorCallback| and {{GeolocationPositionError/PERMISSION_DENIED}}.
    2. Return failure.

Call back with error

When instructed to call back with error, given an {{PositionErrorCallback}}`?` |callback:PositionErrorCallback| and an {{unsigned short}} |code:unsigned short|:

  1. If |callback| is null, return.
  2. Let |error| be a a newly created {{GeolocationPositionError}} instance whose {{GeolocationPositionError/code}} attribute is initialized to |code|.
  3. [=Invoke=] |callback| with |error|.

PositionOptions dictionary 

        dictionary PositionOptions {
          boolean enableHighAccuracy = false;
          [Clamp] unsigned long timeout = 0xFFFFFFFF;
          [Clamp] unsigned long maximumAge = 0;
        };

`enableHighAccuracy` member

The enableHighAccuracy member provides a hint that the application would like to receive the most accurate location data. The intended purpose of this member is to allow applications to inform the implementation that they do not require high accuracy geolocation fixes and, therefore, the implementation MAY avoid using geolocation providers that consume a significant amount of power (e.g. GPS).

`timeout` member

The timeout member denotes the maximum length of time, expressed in milliseconds, before [=acquiring a position=] expires.

The time spent waiting for the document to become visible and for [=check permission|obtaining permission to use the API=] is not included in the period covered by the {{PositionOptions/timeout}} member. The {{PositionOptions/timeout}} member only applies when [=acquiring a position=] begins.

`maximumAge` member

The maximumAge member indicates that the web application is willing to accept a cached position whose age is no greater than the specified time in milliseconds.

`GeolocationPosition` interface 

        [Exposed=Window, SecureContext]
        interface GeolocationPosition {
          readonly attribute GeolocationCoordinates coords;
          readonly attribute DOMTimeStamp timestamp;
        };

`coords` attribute

The coords attribute contains geographic coordinates.

`timestamp` attribute

The timestamp attribute represents the time when the geographic position of the device was acquired.

Internal slots

Instances of {{GeolocationPositionError}} are created with the internal slots in the following table:

Internal slot Description
[[\isHighAccuracy]] A {{boolean}} that records the value of the {{PositionOptions/enableHighAccuracy}} member when this {{GeolocationPosition}} is [=a new GeolocationPosition|created=].

GeolocationCoordinates interface 

        [Exposed=Window, SecureContext]
        interface GeolocationCoordinates {
          readonly attribute double accuracy;
          readonly attribute double latitude;
          readonly attribute double longitude;
          readonly attribute double? altitude;
          readonly attribute double? altitudeAccuracy;
          readonly attribute double? heading;
          readonly attribute double? speed;
        };

`latitude`, `longitude`, and `accuracy` attributes

The latitude and longitude attributes are geographic coordinates specified in decimal degrees.

The accuracy attribute denotes the accuracy level of the latitude and longitude coordinates in meters (e.g., `65` meters).

`altitude` and `altitudeAccuracy` attributes

The altitude attribute denotes the height of the position, specified in meters above the [[WGS84]] ellipsoid.

The altitudeAccuracy attribute represents the altitude accuracy in meters (e.g., `10` meters).

`heading` attribute

The heading attribute denotes the direction of travel of the hosting device and is specified in degrees, where 0° ≤ heading < 360°, counting clockwise relative to the true north.

`speed` attribute

The speed attribute denotes the magnitude of the horizontal component of the hosting device's current velocity in meters per second.

Constructing a `GeolocationPosition`

A new `GeolocationPosition` is constructed with {{DOMTimeStamp}} |timestamp:DOMTimeStamp| and boolean |isHighAccuracy| by performing the following steps:

  1. Let |coords| be a newly created {{GeolocationCoordinates}} instance:
    1. Initialize |coord|'s {{GeolocationCoordinates/latitude}} attribute to a geographic coordinate in decimal degrees.
    2. Initialize |coord|'s {{GeolocationCoordinates/longitude}} attribute to a geographic coordinate in decimal degrees.
    3. Initialize |coord|'s {{GeolocationCoordinates/accuracy}} attribute to a non-negative real number. The value SHOULD correspond to a 95% confidence level with respect to the longitude and latitude values.
    4. Initialize |coord|'s {{GeolocationCoordinates/altitude}} attribute in meters above the [[WGS84]] ellipsoid, or `null` if the implementation cannot provide altitude information.
    5. Initialize |coord|'s {{GeolocationCoordinates/altitudeAccuracy}} attribute as non-negative real number, or to `null` if the implementation cannot provide altitude information. If the altitude accuracy information is provided, it SHOULD correspond to a 95% confidence level.
    6. Initialize |coord|'s {{GeolocationCoordinates/speed}} attribute to a non-negative real number, or as `null` if the implementation cannot provide speed information.
    7. Initialize |coord|'s {{GeolocationCoordinates/heading}} attribute in degrees, or `null` implementation cannot provide heading information. If the hosting device is stationary (i.e. the value of the {{GeolocationCoordinates/speed}} attribute is 0), then initialize the {{GeolocationCoordinates/heading}} to `NaN`.
  2. Return a newly created {{GeolocationPosition}} instance with its {{GeolocationPosition/coords}} attribute initialized to |coords| and {{GeolocationPosition/timestamp}} attribute initialized to |timestamp|, and its {{GeolocationPosition/[[isHighAccuracy]]}} internal slot set to |isHighAccuracy|.

GeolocationPositionError interface 

        [Exposed=Window]
        interface GeolocationPositionError {
          const unsigned short PERMISSION_DENIED = 1;
          const unsigned short POSITION_UNAVAILABLE = 2;
          const unsigned short TIMEOUT = 3;
          readonly attribute unsigned short code;
          readonly attribute DOMString message;
        };

Constants

PERMISSION_DENIED (numeric value 1)
[=Request position=] failed because the user denied permission to use the API.
POSITION_UNAVAILABLE (numeric value 2)
[=Acquire a position=] failed.
TIMEOUT (numeric value 3)
The length of time specified by the {{PositionOptions/timeout}} member has elapsed before the user agent could successfully [=acquire a position=].

`code` attribute

The code attribute returns the value it was [=call back with error|initialized to=] (see [[[#constants]]] for possible values).

`message` attribute

The message attribute is a developer-friendly textual description of the {{GeolocationPositionError/code}} attribute.

Permissions policy

The Geolocation API defines a [=policy-controlled feature=] identified by the string "geolocation". Its [=default allowlist=] is `["self"]`.

Acknowledgments

This specification builds upon earlier work in the industry, including research by Aza Raskin, Google Gears Geolocation API, and LocationAware.org.

Thanks also to Alec Berntson, Alissa Cooper, Steve Block, Greg Bolsinga, Lars Erik Bolstad, Aaron Boodman, Dave Burke, Chris Butler, Max Froumentin, Shyam Habarakada, Marcin Hanclik, Ian Hickson, Brad Lassey, Angel Machin, Cameron McCormack, Daniel Park, Stuart Parmenter, Olli Pettay, Chris Prince, Arun Ranganathan, Carl Reed, Thomas Roessler, Dirk Segers, Allan Thomson, Martin Thomson, Doug Turner, Erik Wilde, Matt Womer, and Mohamed Zergaoui.