Geolocation Functions

geolocationHelper.js

var GeolocationHelper = (function(geolocationHelper){
	'use strict';

	geolocationHelper.getBearing = getBearing;
	geolocationHelper.getDistance = getDistance;

	var _toRad = function(deg) {
		return deg * Math.PI / 180;
	};
	var _toDeg = function(rad) {
		return rad * 180 / Math.PI;
	};

	function getBearing(lat1, lng1, lat2, lng2) {
		var dLon = _toRad(lng2 - lng1);
		var y = Math.sin(dLon) * Math.cos(_toRad(lat2));
		var x = Math.cos(_toRad(lat1)) * Math.sin(_toRad(lat2)) - Math.sin(_toRad(lat1)) * Math.cos(_toRad(lat2)) * Math.cos(dLon);
		var brng = _toDeg(Math.atan2(y, x));

		return ((brng + 360) % 360);
	}

	function getDistance(lat1, lon1, lat2, lon2) {
		var distance = (Math.sin(lat1 * Math.PI) * Math.sin(lat2 * Math.PI)) + (Math.cos(lat1 * Math.PI) * Math.cos(lat2 * Math.PI) * Math.cos(Math.abs(lon1 - lon2) * Math.PI));

		return Math.acos(distance) * 6370981.162;
	}

	return geolocationHelper;
})(GeolocationHelper || {});