Distance between 2 points test

getDistance.js

const quaiFM = [47.2076056402, -1.55753246791];
const testMarker = [47.21, -1.552];
const rdgReze = [47.19316, -1.549212];
const plWalRou = [47.2277747611, -1.55214798607];

// function to calculate distance - expects array of lat / long for each param
// this is no good due to the difference in conversion offset degrees / metres between lat and long!
calcDistance = function (origin, dest) {
    const xOffset = origin[1] - dest[1];
    const yOffset = origin[0] - dest[0];
    const distance = Math.sqrt(xOffset * xOffset + yOffset * yOffset);
    // distance hack - approx value for latitude of Nantes DOESNT WORK, leads to c. 1km error for 4km N / S journey across Nantes
    console.log(distance * 82111);
};

// better function to calculate distance, accurate lat / long offset
function getDistance(origin, destination) {
    function toRadian(degree) {
        return (degree * Math.PI) / 180;
    }
    // return distance in meters
    const lon1 = toRadian(origin[1]);
    const lat1 = toRadian(origin[0]);
    const lon2 = toRadian(destination[1]);
    const lat2 = toRadian(destination[0]);

    const deltaLat = lat2 - lat1;
    const deltaLon = lon2 - lon1;

    const a =
        Math.pow(Math.sin(deltaLat / 2), 2) +
        Math.cos(lat1) * Math.cos(lat2) * Math.pow(Math.sin(deltaLon / 2), 2);
    const c = 2 * Math.asin(Math.sqrt(a));
    const EARTH_RADIUS = 6371;
    return c * EARTH_RADIUS * 1000;
}

console.log(getDistance(rdgReze, plWalRou));
console.log(getDistance(quaiFM, testMarker));