HTML and CSS Reference
In-Depth Information
Table 12-3. Properties of the position Object
Returns the latitude value in decimal format.
Returns the longitude value in decimal format.
Contains a distance in meters that specifies how close the latitude and longitude
values are to the actual location. The value of the accuracy property increases as the
accuracy of the location data decreases.
Returns the height of the user's location in meters above the ellipsoid.
Provides the accuracy of the altitude value in meters.
Indicates the direction of travel in degrees relative to north.
Gives the ground speed in meters per second.
Gives the timestamp at which the location data was returned. It's returned as
number of milliseconds since 1 January 1970. You can convert this value into a
JavaScript Date object for further use.
Not all the properties discussed in Table 12-3 are available on all the devices. For example, a desktop
computer doesn't supply properties such as speed and heading . The four properties latitude , longitude ,
accuracy , and timestamp are available on all devices; the other properties aren't guaranteed to be
supported. If no data is available for a property, null is returned.
The code in Listing 12-2 reads various properties and appends the values in a HTML table ( tblInfo ). If
an error occurs while finding the user location, the OnError() function is called. OnError() is shown in
Listing 12-3.
Listing 12-3. OnError() Function to Display Error Information
function OnError(err) {
alert(err.code + " : " + err.message);
The OnError() function is quite straightforward. The err object passed to the function has two
properties that give more information about the error: code and message . The possible error codes are 1
( PERMISSION_DENIED ), 2 ( POSITION_UNAVAILABLE ), and 3 ( TIMEOUT ). The message property gives a descriptive
error message. Figure 12-3 shows an error message when permission to use the Geolocation API is denied.
Figure 12-3. Error message after permission to use the Geolocation API is denied
Figure 12-3 shows the code and message properties in an alert box. You can, of course, check the code
property and display a friendlier message for each error code.
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