GPS coordinates are not stored in my variables - gps

Question

The following code does not seem to use the location data when performing calcCrow in the for loop for all the locations. When I check it using the Chrome Debugger and go step by step the code never actually gets the coordinates until after the code is completed execution.
var locationsOfInterest = [];
var currentlat= 0;
var currentlong= 0;
x = navigator.geolocation;
x.getCurrentPosition(getposition);
function getposition(position){
currentlat = position.coords.latitude;
currentlong = position.coords.longitude;
};
var sunwayuni = {
title: "Sunway University",
latitude: 3.0681,
longitude: 101.6041,
}
var monashaustralia = {
title: "Monash Australia",
latitude: -37.876823,
longitude: 145.045837,
}
var kualalumpur = {
title: "Kuala Lumpur",
latitude: 3.1390,
longitude: 101.6869,
}
locationsOfInterest= [sunwayuni, monashaustralia, kualalumpur]
for (var i = 0; i < locationsOfInterest.length; i++){
locationsOfInterest[i].distance = calcCrow(locationsOfInterest[i].latitude, locationsOfInterest[i].longitude);
}
function calcCrow(lat2, lon2)
{
var R = 6371; // km
var drLat = toRad(lat2-currentlat);
var drLon = toRad(lon2-currentlong);
var rlat1 = toRad(currentlat);
var rlat2 = toRad(lat2);
var a = Math.sin(drLat/2) * Math.sin(drLat/2) +
Math.sin(drLon/2) * Math.sin(drLon/2) * Math.cos(rlat1) * Math.cos(rlat2);
var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a));
var d = R * c;
return d;
}
// Converts numeric degrees to radians
function toRad(Value)
{
return Value * Math.PI / 180;
}

Answer 1

Html5 getcurrentposition functions works asynchronously so all processing do in getcurrentposition function.
var locationsOfInterest = []; var currentlat= 0; var currentlong= 0; x = navigator.geolocation; x.getCurrentPosition(getposition); function getposition(position){ currentlat = position.coords.latitude; currentlong = position.coords.longitude;
var sunwayuni = { title: "Sunway University", latitude: 3.0681, longitude: 101.6041, } var monashaustralia = { title: "Monash Australia", latitude: -37.876823, longitude: 145.045837, } var kualalumpur = { title: "Kuala Lumpur", latitude: 3.1390, longitude: 101.6869, } locationsOfInterest= [sunwayuni, monashaustralia, kualalumpur] for (var i = 0; i < locationsOfInterest.length; i++){ locationsOfInterest[i].distance = calcCrow(locationsOfInterest[i].latitude, locationsOfInterest[i].longitude); } function calcCrow(lat2, lon2) { var R = 6371; // km var drLat = toRad(lat2-currentlat); var drLon = toRad(lon2-currentlong); var rlat1 = toRad(currentlat); var rlat2 = toRad(lat2); var a = Math.sin(drLat/2) * Math.sin(drLat/2) + Math.sin(drLon/2) * Math.sin(drLon/2) * Math.cos(rlat1) * Math.cos(rlat2); var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a)); var d = R * c; return d; } // Converts numeric degrees to radians function toRad(Value) { return Value * Math.PI / 180; }
};