Refactor google maps singleton

package.json

@@ -1,6 +1,6 @@
 {
   "name": "use-sort-cities-by-distance",
-  "version": "1.0.6",
+  "version": "1.0.7",
   "description": "Sorts an array of cities by proximity to a point",
   "main": "./dist/cjs/index.js",
   "module": "./dist/esm/index.js",

src/helpers/googleMaps.ts

@@ -1,14 +1,24 @@
 import { Loader } from '@googlemaps/js-api-loader'
 
 class GoogleMaps {
-  key: string
+  key!: string
   globalMaps: typeof google.maps | undefined
+  private static instance: GoogleMaps
+  coordinatesCache: Map<string, { lat: number; lng: number } | undefined> = new Map()
 
-  constructor(key: string) {
+  private constructor(key: string) {
     this.key = key
     this.globalMaps = undefined
   }
 
+  public static getInstance(key: string): GoogleMaps {
+    if (!GoogleMaps.instance) {
+      GoogleMaps.instance = new GoogleMaps(key)
+    }
+
+    return GoogleMaps.instance
+  }
+
   async getMaps() {
     if (this.globalMaps) {
       return this.globalMaps
@@ -24,6 +34,10 @@ class GoogleMaps {
   }
 
   async getCoordinates(address: string) {
+    if (this.coordinatesCache.has(address)) {
+      return this.coordinatesCache.get(address)
+    }
+
     const maps = await this.getMaps()
 
     if (!maps) return undefined
@@ -37,7 +51,9 @@ class GoogleMaps {
           return
         }
         const { lat, lng } = results[0].geometry.location
-        resolve({ lat: lat(), lng: lng() })
+        const coordinates = { lat: lat(), lng: lng() }
+        this.coordinatesCache.set(address, coordinates)
+        resolve(coordinates)
       })
     })
   }

src/hooks/useSortCitiesByDistance.tsx

@@ -29,7 +29,7 @@ const useNearestLocation = ({ list, key, start = '', targets = [], unit = 'mile'
   useEffect(() => {
     const sortByDistance = async () => {
       const cities = list ? list : undefined
-      const googleMaps = key ? new GoogleMaps(key) : undefined
+      const googleMaps = key ? GoogleMaps.getInstance(key) : undefined
 
       if (!start || !targets.length || (!list && !key)) {
         return