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 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

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()