JavaScript program to check circle overlapping

geocode-circle-overlap.js

const MILES2METER = 1609.34;
const METER2MILE = 0.000621371;

// JavaScript program to check circles overlapping
function circle(x1, y1, x2, y2, r1, r2) {
	//let distSq = Math.sqrt(((x1 - x2) * (x1 - x2)) + ((y1 - y2) * (y1 - y2)));
	let distSq = getDistanceFromLatLonInMile(x1, y1, x2, y2) * MILES2METER;
	if ( r1 < r2 ) {
		[r1,r2]=[r2,r1];
	}
	if (distSq + r2 <= r1) {
		return 'Complete overlap';
	} else if ( distSq > r2 + r1) {
		return 'Not overlapping';
	} else {
		return 'Overlapping';
	}
}

function getDistanceFromLatLonInMile(lat1, lon1, lat2, lon2) {
	var R = 3959; // Radius of the earth in mile
	var dLat = deg2rad(lat2 - lat1);  // deg2rad below
	var dLon = deg2rad(lon2 - lon1);
	var a = Math.sin(dLat / 2) * Math.sin(dLat / 2) +
		Math.cos(deg2rad(lat1)) * Math.cos(deg2rad(lat2)) * Math.sin(dLon / 2) * Math.sin(dLon / 2);
	var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
	var d = R * c; // Distance in mile
	return d;
}

function deg2rad(deg) {
	return deg * (Math.PI / 180)
}

console.log( circle(43.047461250774695,-108.03926157053738,43.0453134,-108.1903059,34700,16094));