Starting Location (lat, lon):
???°, ???°
Current Location (lat, lon):
???°, ???°
Distance from starting location:
0 km
// check for Geolocation support
if (navigator.geolocation) {
console.log('Geolocation is supported!');
}
else {
console.log('Geolocation is not supported for this Browser/OS version yet.');
}
window.onload = function() {
var startPos;
navigator.geolocation.getCurrentPosition(function(position) {
startPos = position;
document.getElementById('startLat').innerHTML = startPos.coords.latitude;
document.getElementById('startLon').innerHTML = startPos.coords.longitude;
});
};
window.onload = function() {
var startPos;
navigator.geolocation.getCurrentPosition(function(position) {
// same as above
}, function(error) {
alert('Error occurred. Error code: ' + error.code);
// error.code can be:
// 0: unknown error
// 1: permission denied
// 2: position unavailable (error response from locaton provider)
// 3: timed out
});
};
navigator.geolocation.watchPosition(function(position) {
document.getElementById('currentLat').innerHTML = position.coords.latitude;
document.getElementById('currentLon').innerHTML = position.coords.longitude;
});
navigator.geolocation.watchPosition(function(position) {
// same as above
document.getElementById('distance').innerHTML =
calculateDistance(startPos.coords.latitude, startPos.coords.longitude,
position.coords.latitude, position.coords.longitude);
});
function calculateDistance(lat1, lon1, lat2, lon2) {
var R = 6371; // km
var dLat = (lat2 - lat1).toRad();
var dLon = (lon2 - lon1).toRad();
var a = Math.sin(dLat / 2) * Math.sin(dLat / 2) +
Math.cos(lat1.toRad()) * Math.cos(lat2.toRad()) *
Math.sin(dLon / 2) * Math.sin(dLon / 2);
var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
var d = R * c;
return d;
}
Number.prototype.toRad = function() {
return this * Math.PI / 180;
}
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