Find the distance between 2 locations given.

haversine_find_2_locs.js

export const findDistanceOf2Locations = ({ target, source }: {
    target: { lat: number, lon: number, fencingRadius: number },
    source: { lat: number, lon: number }
}): {
    distance: number,
    isInside: boolean,
    distancePretty: string // Format the distance in meters or kilometers (e.g. 100m or 1.5km)
} => {
    const { lat: lat1, lon: lon1 } = source;
    const { lat: lat2, lon: lon2, fencingRadius } = target;

    const R = 6371000; // Radius of Earth in meters
    const toRadians = (degrees) => degrees * (Math.PI / 180);

    const phi1 = toRadians(lat1);
    const phi2 = toRadians(lat2);
    const deltaPhi = toRadians(lat2 - lat1);
    const deltaLambda = toRadians(lon2 - lon1);

    const a = Math.sin(deltaPhi / 2) ** 2 +
        Math.cos(phi1) * Math.cos(phi2) *
        Math.sin(deltaLambda / 2) ** 2;
    const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));

    const distance = R * c; // Output distance in meters
    const isInside = distance <= fencingRadius;
    return {
        distance,
        isInside,
        distancePretty: distance < 1000 ? `${distance.toFixed(0)}m` : `${(distance / 1000).toFixed(1)}km`
    };
};


const ouput = findDistanceOf2Locations({
    target: { lat: 11.11, lon: 104.11, fencingRadius: 100 },
    source: { lat: 11.11, lon: 104.11 }
});

console.log(ouput);

haversine_find_2_locs.py

import math

def haversine(lat1, lon1, lat2, lon2):
    R = 6371000  # Radius of Earth in meters
    phi1 = math.radians(lat1)
    phi2 = math.radians(lat2)
    delta_phi = math.radians(lat2 - lat1)
    delta_lambda = math.radians(lon2 - lon1)

    a = math.sin(delta_phi / 2.0) ** 2 + \
        math.cos(phi1) * math.cos(phi2) * math.sin(delta_lambda / 2.0) ** 2
    c = 2 * math.atan2(math.sqrt(a), math.sqrt(1 - a))

    distance = R * c  # Output distance in meters
    return distance

# Example coordinates
lat1, lon1 = xxx, xxx  # Target Location
lat2, lon2 = xxx, xxx  # Source Location

distance = haversine(lat1, lon1, lat2, lon2)
print(f"Distance: {distance} meters")

# Check if within the fencing radius
fencing_radius = 100  # 100 meters
if distance <= fencing_radius:
    print("Source is within the target's radius.")
else:
    print("Source is outside the target's radius.")