fix: 🐛 fix clearCache not working (#37)

fixes #24

Author: thkruz

__tests__/sgp4.js

@@ -1,4 +1,5 @@
 import {
+	getCacheSizes,
 	clearCache,
 	clearTLEParseCache,
 	getGroundTracks,
@@ -109,6 +110,25 @@ describe("getLatLngObj", () => {
 	});
 });
 
+describe('clearCache', () => {
+	test('clears the cache', () => {
+		const timestamp = 1501039268000;
+		const bigBearLatLng = {
+			lat: 34.243889,
+			lng: -116.911389
+		};
+		getSatelliteInfo(
+			tleStr,
+			timestamp,
+			bigBearLatLng.lat,
+			bigBearLatLng.lng
+		);
+		expect(getCacheSizes()).toEqual([3,0,0,0]);
+		clearCache();
+		expect(getCacheSizes()).toEqual([0,0,0,0]);
+	});
+});
+
 describe("getOrbitTrack", () => {
 	beforeEach(() => {
 		clearCache();

src/sgp4.js

@@ -54,8 +54,8 @@ export function getCacheSizes() {
  * Clears SGP caches to free up memory for long-running apps.
  */
 export function clearCache() {
-	caches.forEach(cache => {
-		caches[cache] = {};
+	caches.forEach((_cache, idx) => {
+		caches[idx] = {};
 	});
 }