calcDistanceBetweenTwoPoints.js

/**
 * Calculate the distance between two points on Earth using the Haversine formula
 * @param Point1 { lat: number; lng: number } - The first point
 * @param Point2 { lat: number; lng: number } - The second point
 * @returns Distance in metres
 */
function calcDistanceInMetresBetweenTwoPoints(Point1, Point2) {
  const EARTH_RADIUS_METERS = 6371000; // Earth's radius in meters

  // Convert degrees to radians
  const lat1Rad = Point1.lat * (Math.PI / 180);
  const lng1Rad = Point1.lng * (Math.PI / 180);
  const lat2Rad = Point2.lat * (Math.PI / 180);
  const lng2Rad = Point2.lng * (Math.PI / 180);

  // Calculate differences
  const deltaLatitude = lat2Rad - lat1Rad;
  const deltaLongitude = lng2Rad - lng1Rad;

  // Haversine formula
  const angle = Math.sin(deltaLatitude / 2) ** 2 + 
        Math.cos(lat1Rad) * Math.cos(lat2Rad) * Math.sin(deltaLongitude / 2) ** 2;
 
  const theta = 2 * Math.atan2(Math.sqrt(angle), Math.sqrt(1 - angle));
  
  const distance = EARTH_RADIUS_METERS * theta;

  // Return distance in metres
  return distance;
}

// Test
const PointA = { lat: -33.84887785692942, lon: 151.2106926524797 };
const PointB = { lat: -33.85469551244261, lon: 151.22570778047384 };
const result = calcDistanceInMetresBetweenTwoPoints(PointA, PointB);

console.log(result); // 1530.0543614899987 metres

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