The HTML Geolocation API is used for locating the position of a user.
Locate the User's Position
The HTML Geolocation API is used for locating the position of a user.
As this can be vulnerable to privacy, the position cannot be madet available unless and until the user approves it.
Note: Geolocation is very accurate for electronic gadgets with GPS, like iPhone.
Browser Support
The table numbers specifies the first browser version which fully supports Geolocation.
| API | |||||
|---|---|---|---|---|---|
| Geolocation | 5.0 - 49.0 (http) 50.0 (https) |
9.0 | 3.5 | 5.0 | 16.0 |
Note: As of Chrome 50, the Geolocation API will be only working on secure contexts such as HTTPS. If your site is getting hosted on an non-secure origin (such as HTTP) the requests for getting the users location will not function.
Using HTML Geolocation
The getCurrentPosition() method is used for getting the user's position.
The example below illustrates how it returns user's position in terms of lattitude and longitude:
Example
<script>
var x = document.getElementById("demo");
function
getLocation() {
if (navigator.geolocation) {
navigator.geolocation.getCurrentPosition(showPosition);
} else {
x.innerHTML = "Geolocation is not supported by this
browser.";
}
}
function showPosition(position) {
x.innerHTML = "Latitude:
" + position.coords.latitude +
"<br>Longitude: " + position.coords.longitude;
}
</script>
Try it Yourself
Example explained:
The example stated above can be said to be a very basic Geolocation script, without any error handling.
Handling Errors and Rejections
The second parameter of the getCurrentPosition() method is used for handling errors. It instructs a function to run incase if there is a failure to get the user's location:
Example
function showError(error) {
switch(error.code)
{
case error.PERMISSION_DENIED:
x.innerHTML = "User denied the request for Geolocation."
break;
case error.POSITION_UNAVAILABLE:
x.innerHTML = "Location information is unavailable."
break;
case error.TIMEOUT:
x.innerHTML = "The request to get user location timed out."
break;
case error.UNKNOWN_ERROR:
x.innerHTML = "An unknown error occurred."
break;
}
}
Try it Yourself
Location-specific Information
This page is used for demonstration purpose on how to show a user's position on a map.
Geolocation is also highly useful for getting location-specific information, like:
The getCurrentPosition() Method - Return Data
The getCurrentPosition() method will return an object if it is successful. The properties such as latitude, longitude and accuracy are returned. The other properties are also returned if they are available:
| Property | Returns |
|---|---|
| coords.latitude | The latitude is returned as a decimal number (always returned) |
| coords.longitude | The longitude is returned as a decimal number (always returned) |
| coords.accuracy | The position accuracy (always returned) |
| coords.altitude | The altitude is returned in meters above the mean sea level (returned if available) |
| coords.altitudeAccuracy | The position altitude accuracy (returned if available) |
| coords.heading | The heading measured in degrees clockwise from North (returned if available) |
| coords.speed | The speed measured in meters per second (returned if available) |
| timestamp | The response date/time (returned if available) |
Geolocation object - Other interesting Methods
The Geolocation object is also known to have other interesting methods:
The example given below will show the watchPosition() method. You must be having an accurate GPS device for testing this (like iPhone):
Example
<script>
var x = document.getElementById("demo");
function
getLocation() {
if (navigator.geolocation) {
navigator.geolocation.watchPosition(showPosition);
} else {
x.innerHTML = "Geolocation is not supported by this
browser.";
}
}
function showPosition(position) {
x.innerHTML = "Latitude:
" + position.coords.latitude +
"<br>Longitude: " + position.coords.longitude;
}
</script>
Try it Yourself