Explain Geolocation API in HTML5

The HTML Geolocation API is used to get the geographical position of a user.

Since this can compromise privacy, the position is not available unless the user approves it.

Geolocation Object - Methods

• getCurrentPosition() - Returns the current position of the user.
• watchPosition() - Returns the current position of the user and continues to return updated position as the user moves (like the GPS in a car).
• clearWatch() - Stops the watchPosition() method.

Return Data

• coords.latitude - The latitude as a decimal number. (always returned)
• coords.longitude - The longitude as a decimal number. (always returned)
• coords.accuracy - The accuracy of position. (always returned)
• coords.altitude - The altitude in meters above the mean sea level. (returned if available)
• coords.altitudeAccuracy - The altitude accuracy of position. (returned if available)
• coords.heading - The heading as degrees clockwise from North. (returned if available)
• coords.speed - The speed in meters per second. (returned if available)
• timestamp - The date/time of the response. (returned if available)

Handling Errors and Rejections

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;
  }
}

Example

<script>
function getLocation() {
  if (navigator.geolocation) {
    navigator.geolocation.getCurrentPosition(showPosition, showError);
  } else { 
    alert("Geolocation is not supported by this browser.");
  }
}


function showPosition(position) {
  alert("Latitude: " + position.coords.latitude + ", Longitude: " + position.coords.longitude);
}


function showError(error) {
  switch(error.code) {
    case error.PERMISSION_DENIED:
      alert("User denied the request for Geolocation.");
      break;
    case error.POSITION_UNAVAILABLE:
      alert("Location information is unavailable.");
      break;
    case error.TIMEOUT:
      alert("The request to get user location timed out.");
      break;
    case error.UNKNOWN_ERROR:
      alert("An unknown error occurred.");
      break;
  }
}
</script>