Geolocation.watchPosition

The Geolocation.watchPosition() method is used to register a handler function that will be called automatically each time the position of the device changes. You can also, optionally, specify an error handling callback function.

This method returns a watch ID value that then can be used to unregister the handler by passing it to the Geolocation.clearWatch() method.

Syntax

id = navigator.geolocation.watchPosition(success[, error[, options]])

Parameters

success

A callback function that takes a Position object as an input parameter.

error Optional

An optional callback function that takes a PositionError object as an input parameter.

options Optional

An optional PositionOptions object.

Example

var id, target, options;

function success(pos) {
  var crd = pos.coords;

  if (target.latitude === crd.latitude && target.longitude === crd.longitude) {
    console.log('Congratulations, you reached the target');
    navigator.geolocation.clearWatch(id);
  }
}

function error(err) {
  console.warn('ERROR(' + err.code + '): ' + err.message);
}

target = {
  latitude : 0,
  longitude: 0
};

options = {
  enableHighAccuracy: false,
  timeout: 5000,
  maximumAge: 0
};

id = navigator.geolocation.watchPosition(success, error, options);

Note

If your application is running on firefox OS, please take a look at geolocation wake lock to keep your application getting position updates while in the background or screen off.

Specifications

Specification	Status	Comment
Geolocation API The definition of 'Geolocation.watchPosition()' in that specification.	Recommendation	Initial specification.

Browser compatibility

See also

• geolocation wake lock
• Using geolocation
• The interface it belongs to, Geolocation, and the way to access it NavigatorGeolocation.geolocation.
• The opposite operation: Geolocation.clearWatch()
• A similar method: Geolocation.getCurrentPosition()