HTML Geolocation
In this article, we will know HTML Geolocation, various properties, methods & their implementation through examples.
Geo-location in HTML5 is used to share the location with some websites and be aware of the exact location. It is mainly used for local businesses, and restaurants, or showing locations on the map. It uses JavaScript to give latitude and longitude to the backend server. Most browsers support Geolocation API. Geo-location API uses a global navigator object which can be created as follows:
Syntax:
var loc = navigator.geolocation
Location Properties: The following table determines properties used in getCurrentPosition() and their returning values.
- coords.latitude: Always returns latitude as a decimal number.
- coords.accuracy: Always returns the accuracy of position.
- coords.longitude: Always returns longitude as a decimal number.
- coords.altitude: Returns the altitude in meters above sea level if available.
- coords.altitudeAccuracy: Returns altitude accuracy of position if available.
- coords.heading: Returns heading in degree clockwise from North if available
- coords.speed: Returns speed in mps, if available.
- timestamp: Returns date or time of response if available
Geolocation Methods: The Geolocation has following methods which make it interesting and easier to work.
- getCurrentPosition(): It fetches the current location of the user.
- watchPosition(): It fetches periodic updates of the user’s current location.
- clearWatch(): It cancels a watchPosition call currently in execution.
Example: This example explains returning the user’s current location using the getCurrentPosition() method.
HTML
var loc = navigator.geolocation;function getLoc() { loc.getCurrentPosition(showLoc, errHand);} |
The above function can also be written without creating a navigator object as shown below:
HTML
function getlocation() { navigator.geolocation.getCurrentPosition(showLoc, errHand);} |
Example: In this example, we simply display the current location with the help of latitude and longitude via HTML Geolocation.
HTML
<!DOCTYPE html><html><body> <p>Displaying location using Latitude and Longitude</p> <button class="geeks" onclick="getlocation()"> Click Me </button> <p id="demo1"></p> <script> var variable1 = document.getElementById("demo1"); function getlocation() { navigator.geolocation.getCurrentPosition(showLoc); } function showLoc(pos) { variable1.innerHTML = "Latitude: " + pos.coords.latitude + "<br>Longitude: " + pos.coords.longitude; } </script></body></html> |
Output:
Getting the current location using latitude and longitude
Error and Rejection Handling: It is very important to handle the errors generated in Geolocation and show a required message when an error occurs. Functions like getCurrentPosition() make use of an error handler to handle the error generated (function errHand as used in the above example). The PositionError object used by the error handler has two properties that let the function handle error efficiently.
- Code
- Message
Generated errors in geolocation:
| Error | Error Description |
|---|---|
| UNKNOWN_ERRROR | An unknown error |
| PERMISSION_DENIED | The application doesn’t have permission to make use of location services |
| POSITION_UNAVAILABLE | The location of the device is uncertain |
| TIMEOUT | The time to fetch location information exceeded the maximum timeout interval |
Example: This example shows the above-approach.
HTML
<!DOCTYPE html><html><head> <title>Errors in geolocation</title> <style> .gfg { font-size: 40px; font-weight: bold; color: #009900; margin-left: 20px; } .geeks { margin-left: 150px; } p { font-size: 20px; margin-left: 20px; } </style></head><body> <div class="gfg">GeeksforGeeks</div> <p>Error handling in geolocation</p> <button class="geeks" onclick="getlocation()"> Click </button> <p id="demo1"></p> <script> var variable1 = document.getElementById("demo1"); function getlocation() { navigator.geolocation.getCurrentPosition(showLoc, errHand); } function showLoc(pos) { variable1.innerHTML = "Latitude: " + pos.coords.latitude + "<br>Longitude: " + pos.coords.longitude; } function errHand(err) { switch (err.code) { case err.PERMISSION_DENIED: variable1.innerHTML = "The application doesn't have the" + "permission to make use of location services"; break; case err.POSITION_UNAVAILABLE: variable1.innerHTML = "The location of the device is uncertain"; break; case err.TIMEOUT: variable1.innerHTML = "The request to get user location timed out"; break; case err.UNKNOWN_ERROR: variable1.innerHTML = "Time to fetch location information exceeded" + "the maximum timeout interval"; break; } } </script></body></html> |
Output:
Error handling in Geolocation
Displaying result in MAP: Displaying location on a map is a very interesting task. These services are used to provide the exact location on the map.
Example: This example describes getting the current position in Google Maps with the help of latitude and longitude via HTML Geolocation.
HTML
<!DOCTYPE html><html><head> <title>Display location in map</title> <style> .gfg { font-size: 40px; font-weight: bold; color: #009900; margin-left: 20px; } .geeks { margin-left: 150px; } p { font-size: 20px; margin-left: 20px; } </style></head><body> <div class="gfg">GeeksforGeeks</div> <p>Display location in map</p> <button class="geeks" type="button" onclick="getlocation();"> Current Position </button> <div id="demo2" style="width: 500px; height: 500px"></div> </script> <script type="text/javascript"> function getlocation() { if (navigator.geolocation) { navigator.geolocation.getCurrentPosition(showLoc, errHand); } } function showLoc(pos) { latt = pos.coords.latitude; long = pos.coords.longitude; var lattlong = new google.maps.LatLng(latt, long); var OPTions = { center: lattlong, zoom: 10, mapTypeControl: true, navigationControlOptions: { style: google.maps.NavigationControlStyle.SMALL, }, }; var mapg = new google.maps.Map( document.getElementById("demo2"), OPTions ); var markerg = new google.maps.Marker({ position: lattlong, map: mapg, title: "You are here!", }); } function errHand(err) { switch (err.code) { case err.PERMISSION_DENIED: result.innerHTML = "The application doesn't have the permission" + "to make use of location services"; break; case err.POSITION_UNAVAILABLE: result.innerHTML = "The location of the device is uncertain"; break; case err.TIMEOUT: result.innerHTML = "The request to get user location timed out"; break; case err.UNKNOWN_ERROR: result.innerHTML = "Time to fetch location information exceeded" + "the maximum timeout interval"; break; } } </script></body></html> |
Output:
Getting the current position in Google Map
Supported Browsers:
- Google Chrome 5 and above
- Microsoft Edge 12 and above
- Firefox 3.5 and above
- Internet Explorer 9 and above
- Opera 10.6 and above
- Safari 5 and above
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