Geolocation.clearWatch()

var id, target, option;

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

  if (target.latitude === crd.latitude && target.longitude === crd.longitude) {
    console.log('Congratulation, you reach 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);