Calculate distance and speed by latitude and longitude. es6 javascript

calculate_ds.js

const calculate_ds = (lat1, lon1, lat2, lon2, timestamp1, timestamp2) => {

	lat1 = lat1 * Math.PI / 180.0;
	lon1 = lon1 * Math.PI / 180.0;

	lat2 = lat2 * Math.PI / 180.0;
	lon2 = lon2 * Math.PI / 180.0;

	const r = 6378100;

	const rho1 = r * Math.cos(lat1);
	const z1 = r * Math.sin(lat1);
	const x1 = rho1 * Math.cos(lon1);
	const y1 = rho1 * Math.sin(lon1);

	const rho2 = r * Math.cos(lat2);
	const z2 = r * Math.sin(lat2);
	const x2 = rho2 * Math.cos(lon2);
	const y2 = rho2 * Math.sin(lon2);

	const dot = (x1 * x2 + y1 * y2 + z1 * z2);
	const cos_theta = dot / (r * r);

	const theta = Math.acos(cos_theta);

	const distance = r * theta;
	const time_s = (timestamp2 - timestamp1);
	const speed_mps = distance / time_s;
	const speed_kph = (speed_mps * 3600.0) / 1000.0;

	return { distance, time_s, speed_mps, speed_kph };

}

calculate_ds(53.232863,44.899063,53.232858,44.898095,1512512341,1512512346)