useDistance - Hook to simplify distance measurement (Geo)

useDistance.ts

import { useMemo } from 'react'

type GeoLocation = {
  latitude: number
  longitude: number
}

export const useDistance = (pointA?: GeoLocation, pointB?: GeoLocation) =>
  useMemo(() => {
    const isValid = x => x != null && isFinite(x)
    if (
      !(
        isValid(pointA?.latitude) &&
        isValid(pointA?.longitude) &&
        isValid(pointB?.latitude) &&
        isValid(pointB?.longitude)
      )
    ) {
      return null
    }

    const deg2rad = (deg: number) => deg * (Math.PI / 180)
    const kmToMiles = (km: number) => km / 1.609344

    const latA = pointA?.latitude ?? 0
    const lonA = pointA?.longitude ?? 0

    const latB = pointB?.latitude ?? 0
    const lonB = pointB?.longitude ?? 0

    const equatorialRadius = 6371 // Radius of the earth in km
    const dLat = deg2rad(latB - latA) // deg2rad below
    const dLon = deg2rad(lonB - lonA)
    const a =
      Math.sin(dLat / 2) * Math.sin(dLat / 2) +
      Math.cos(deg2rad(latA)) * Math.cos(deg2rad(latB)) * Math.sin(dLon / 2) * Math.sin(dLon / 2)

    const angle = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a))
    const distanceKm = equatorialRadius * angle // Distance in km

    return kmToMiles(distanceKm)
  }, [pointA?.latitude, pointA?.longitude, pointB?.latitude, pointB?.longitude])