Calculate distance between 2 GPS coordinates

gistfile1.js

	/**
	 *	Distance between two points
	 * 	@param coords1 {lat: xx, lng: yy}
	 * 	@param coords2 {lat: xx, lng: yy}
	 * 	@returnd distance in meters
	 */
	function _getCoordsDistance(coords1, coords2)
	{
		// earth
		var R = 6371, // km
			lat1 = parseFloat(coords1.lat),
			lat2 = parseFloat(coords2.lat),
			lon1 = parseFloat(coords1.lng),
			lon2 = parseFloat(coords2.lng);
		
		// deg2rad
		lat1 = (lat1 / 180) * Math.PI;
		lat2 = (lat2 / 180) * Math.PI;
		lon1 = (lon1 / 180) * Math.PI;
		lon2 = (lon2 / 180) * Math.PI;
			
	    // Equirectangular approximation
	    // lower accuracy, higher performance
	    var x = (lon2-lon1) * Math.cos((lat1+lat2)/2);
		var y = (lat2-lat1);
		var d = Math.sqrt(x*x + y*y) * R;
		return Math.round(d * 1000);
	}