This method returns the watchId value that uniquely identifies a watch
operation. Then it asynchronously starts the watch operation, which first attempts to obtain
the current location of the device.
If the attempt is successful, the successCallback method is
invoked with a new Position object. If the attempt fails, the
errorCallback method is called with a new PositionError
object. The watch operation then continues to monitor the position of the device and invokes
the appropriate callback periodically, depending on the settings defined in the
options parameter, until the clearWatch
method is called.
| Name | Description | Type | Use |
|---|---|---|---|
| successCallback | A callback function called to pass the device's current position. | function |
required |
| errorCallback | A callback function called to pass an error. | function |
optional |
| options | A PositionOptions object, used to configure the API's responsiveness.
Refer to the object's description for default values of individual parameters. |
object |
optional |
The table below lists the parameters supported by the
successCallback callback.
| Parameter | Description | Type |
|---|---|---|
| Position | The geolocation position returned by the device through a callback function. | object |
The table below lists the parameters supported by the
errorCallback callback.
| Parameter | Description | Type |
|---|---|---|
| PositionError | Geolocation error object returned through a callback function. | object |