Geolocation.watchPosition() - Web APIs 编辑

Secure context

This feature is available only in secure contexts (HTTPS), in some or all supporting browsers.

The Geolocation method 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.

Syntax

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

Parameters

success

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

error Optional

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

options Optional

An optional PositionOptions object that provides configuration options for the location watch.

Return value

An integer ID that identifies the registered handler. The ID can be passed to the Geolocation.clearWatch() to unregister the handler.

Examples

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);

Specifications

Browser compatibility

BCD tables only load in the browser

See also

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