heading property

The heading read-only property of the GeolocationCoordinates interface is a double representing the direction in which the device is traveling. This value, specified in degrees, indicates how far off from heading due north the device is. 0 degrees represents true north, and the direction is determined clockwise (which means that east is 90 degrees and west is 270 degrees). If GeolocationCoordinates.speed is 0, heading is NaN. If the device is not able to provide heading information, this value is null.