refactor: ttl and createdAt instead of maxAge and storage takes care of staled entries

.eslintrc

@@ -9,6 +9,11 @@
   "parser": "@typescript-eslint/parser",
   "plugins": ["@typescript-eslint"],
   "root": true,
+  "env": {
+    "browser": true,
+    "amd": true,
+    "node": true
+  },
   "rules": {
     "@typescript-eslint/explicit-module-boundary-types": "off",
     "@typescript-eslint/no-empty-function": "off",

src/axios/cache.ts

@@ -21,7 +21,7 @@ export function createCache(
   axiosCache.defaults = {
     ...axios.defaults,
     cache: {
-      maxAge: 1000 * 60 * 5,
+      ttl: 1000 * 60 * 5,
       interpretHeader: false,
       methods: ['get'],
       cachePredicate: ({ status }) => status >= 200 && status < 300,

src/axios/types.ts

@@ -25,13 +25,15 @@ export type CacheProperties = {
   /**
    * The time until the cached value is expired in milliseconds.
    *
-   * @default 1000 * 60 * 5
+   * **Note**: a custom storage implementation may not respect this.
+   *
+   * @default 1000 * 60 * 5 // 5 Minutes
    */
-  maxAge: number;
+  ttl: number;
 
   /**
    * If this interceptor should configure the cache from the request cache header
-   * When used, the maxAge property is ignored
+   * When used, the ttl property is ignored
    *
    * @default false
    */

src/interceptors/request.ts

@@ -14,6 +14,8 @@ export function applyRequestInterceptor(axios: AxiosCacheInstance): void {
     }
 
     const key = axios.generateKey(config);
+
+    // Assumes that the storage handled staled responses
     const cache = await axios.storage.get(key);
 
     // Not cached, continue the request, and mark it as fetching
@@ -22,17 +24,13 @@ export function applyRequestInterceptor(axios: AxiosCacheInstance): void {
       axios.waiting[key] = new Deferred();
 
       await axios.storage.set(key, {
-        state: 'loading'
+        state: 'loading',
+        ttl: config.cache?.ttl
       });
 
       return config;
     }
 
-    if (cache.state === 'cached' && cache.expiration < Date.now()) {
-      await axios.storage.remove(key);
-      return config;
-    }
-
     let data: CachedResponse = {};
 
     if (cache.state === 'loading') {

src/interceptors/response.ts

@@ -30,7 +30,7 @@ export function applyResponseInterceptor(axios: AxiosCacheInstance): void {
       return response;
     }
 
-    let expiration = Date.now() + (response.config.cache?.maxAge || axios.defaults.cache.maxAge);
+    let ttl = response.config.cache?.ttl || axios.defaults.cache.ttl;
 
     if (response.config.cache?.interpretHeader) {
       const expirationTime = axios.headerInterpreter(response.headers['cache-control']);
@@ -42,13 +42,14 @@ export function applyResponseInterceptor(axios: AxiosCacheInstance): void {
         return response;
       }
 
-      expiration = expirationTime ? expirationTime : expiration;
+      ttl = expirationTime ? expirationTime : ttl;
     }
 
     const newCache: CachedStorageValue = {
       data: { body: response.data, headers: response.headers },
       state: 'cached',
-      expiration: expiration
+      ttl: ttl,
+      createdAt: Date.now()
     };
 
     // Update other entries before updating himself

src/storage/memory.ts

@@ -1,19 +1,21 @@
-import { EmptyStorageValue } from '.';
 import { CacheStorage, StorageValue } from './types';
 
 export class MemoryStorage implements CacheStorage {
-  readonly storage: Map<string, StorageValue> = new Map();
+  private readonly storage: Map<string, StorageValue> = new Map();
 
   get = async (key: string): Promise<StorageValue> => {
     const value = this.storage.get(key);
 
-    if (value) {
-      return value;
+    if (!value) {
+      return { state: 'empty' };
     }
 
-    const empty: EmptyStorageValue = { state: 'empty' };
-    this.storage.set(key, empty);
-    return empty;
+    if (value.state === 'cached' && value.createdAt + value.ttl < Date.now()) {
+      this.remove(key);
+      return { state: 'empty' };
+    }
+
+    return value;
   };
 
   set = async (key: string, value: StorageValue): Promise<void> => {

src/storage/types.ts

@@ -1,15 +1,17 @@
 export interface CacheStorage {
   /**
-   * Returns the cached value for the given key. Should return a 'empty'
-   * state StorageValue if the key does not exist.
+   * Returns the cached value for the given key.
+   * Must handle cache miss and staling by returning a new `StorageValue` with `empty` state.
    */
   get: (key: string) => Promise<StorageValue>;
+
   /**
    * Sets a new value for the given key
    *
    * Use CacheStorage.remove(key) to define a key to 'empty' state.
    */
   set: (key: string, value: LoadingStorageValue | CachedStorageValue) => Promise<void>;
+
   /**
    * Removes the value for the given key
    */
@@ -28,18 +30,29 @@ export type StorageValue = CachedStorageValue | LoadingStorageValue | EmptyStora
 
 export type CachedStorageValue = {
   data: CachedResponse;
-  expiration: number;
+  ttl: number;
+  createdAt: number;
   state: 'cached';
 };
 
 export type LoadingStorageValue = {
   data?: undefined;
-  expiration?: undefined;
+  ttl?: number;
+
+  /**
+   * Defined when the state is cached
+   */
+  createdAt?: undefined;
   state: 'loading';
 };
 
 export type EmptyStorageValue = {
   data?: undefined;
-  expiration?: undefined;
+  ttl?: undefined;
+
+  /**
+   * Defined when the state is cached
+   */
+  createdAt?: undefined;
   state: 'empty';
 };

src/storage/web.ts

@@ -5,9 +5,22 @@ import { CacheStorage, StorageValue } from './types';
 export abstract class WindowStorageWrapper implements CacheStorage {
   constructor(readonly storage: Storage, readonly prefix: string = 'axios-cache:') {}
 
-  get = async (key: string): Promise<StorageValue> => {
-    const json = this.storage.getItem(this.prefix + key);
-    return json ? JSON.parse(json) : { state: 'empty' };
+  get = async (_key: string): Promise<StorageValue> => {
+    const key = this.prefix + _key;
+    const json = this.storage.getItem(key);
+
+    if (!json) {
+      return { state: 'empty' };
+    }
+
+    const parsed = JSON.parse(json);
+
+    if (parsed.state === 'cached' && parsed.createdAt + parsed.ttl < Date.now()) {
+      this.storage.removeItem(key);
+      return { state: 'empty' };
+    }
+
+    return parsed;
   };
 
   set = async (key: string, value: StorageValue): Promise<void> => {
@@ -22,7 +35,7 @@ export abstract class WindowStorageWrapper implements CacheStorage {
 
 export class LocalCacheStorage extends WindowStorageWrapper {
   constructor(prefix?: string) {
-    super(window.localStorage, prefix);
+    super(window.localStorage || localStorage, prefix);
   }
 }
 

test/storage/common.test.ts

@@ -0,0 +1,6 @@
+import { MemoryStorage } from '../../src/storage';
+import { testStorage } from './storages';
+
+describe('tests common storages', () => {
+  testStorage('memory', MemoryStorage);
+});

test/storage/storages.ts

@@ -0,0 +1,60 @@
+import { CacheStorage } from '../../src/storage/types';
+
+export function testStorage(name: string, Storage: { new (): CacheStorage }) {
+  it(`tests ${name} storage methods`, async () => {
+    const storage = new Storage();
+
+    const result = await storage.get('key');
+
+    expect(result).not.toBeNull();
+    expect(result.state).toBe('empty');
+
+    await storage.set('key', {
+      state: 'cached',
+      createdAt: Date.now(),
+      ttl: 1000 * 60 * 5,
+      data: { body: 'data', headers: {} }
+    });
+
+    const result2 = await storage.get('key');
+
+    expect(result2).not.toBeNull();
+    expect(result2.state).toBe('cached');
+    expect(result2.data?.body).toBe('data');
+
+    await storage.remove('key');
+
+    const result3 = await storage.get('key');
+
+    expect(result3).not.toBeNull();
+    expect(result3.state).toBe('empty');
+  });
+
+  it(`tests ${name} storage staling`, async () => {
+    jest.useFakeTimers('modern');
+    const storage = new Storage();
+
+    await storage.set('key', {
+      state: 'cached',
+      createdAt: Date.now(),
+      ttl: 1000 * 60 * 5, // 5 Minutes
+      data: { body: 'data', headers: {} }
+    });
+
+    const result = await storage.get('key');
+
+    expect(result).not.toBeNull();
+    expect(result.state).toBe('cached');
+    expect(result.data?.body).toBe('data');
+
+    // Advance 6 minutes in time
+    jest.setSystemTime(Date.now() + 1000 * 60 * 6);
+
+    const result2 = await storage.get('key');
+
+    expect(result2).not.toBeNull();
+    expect(result2.state).toBe('empty');
+
+    jest.useRealTimers();
+  });
+}

test/storage/web.test.ts

@@ -0,0 +1,11 @@
+/**
+ * @jest-environment jsdom
+ */
+
+import { LocalCacheStorage, SessionCacheStorage } from '../../src/storage';
+import { testStorage } from './storages';
+
+describe('tests web storages', () => {
+  testStorage('local-storage', LocalCacheStorage);
+  testStorage('session-storage', SessionCacheStorage);
+});

test/util/status-codes.test.ts

@@ -12,7 +12,8 @@ describe('Tests cached status code', () => {
 
     axios.storage.set(KEY, {
       data: { body: true },
-      expiration: Infinity,
+      ttl: Infinity,
+      createdAt: Date.now(),
       state: 'cached'
     });
   });

test/util/update-cache.test.ts

@@ -1,11 +1,16 @@
-import { AxiosCacheInstance, StorageValue } from '../../src';
+import { AxiosCacheInstance, CachedStorageValue } from '../../src';
 import { updateCache } from '../../src/util/update-cache';
 import { mockAxios } from '../mocks/axios';
 
 const KEY = 'cacheKey';
 const EMPTY_STATE = { state: 'empty' };
 const DEFAULT_DATA = 'random-data';
-const INITIAL_DATA: StorageValue = { data: { body: true }, expiration: Infinity, state: 'cached' };
+const INITIAL_DATA: CachedStorageValue = {
+  data: { body: true },
+  createdAt: Date.now(),
+  ttl: Infinity,
+  state: 'cached'
+};
 
 describe('Tests update-cache', () => {
   let axios: AxiosCacheInstance;
@@ -42,7 +47,8 @@ describe('Tests update-cache', () => {
     await updateCache(axios, DEFAULT_DATA, {
       [KEY]: (cached, newData) => ({
         state: 'cached',
-        expiration: Infinity,
+        ttl: Infinity,
+        createdAt: Date.now(),
         data: { body: `${cached.data?.body}:${newData}` }
       })
     });
@@ -53,6 +59,6 @@ describe('Tests update-cache', () => {
     expect(response).not.toStrictEqual(EMPTY_STATE);
 
     expect(response.state).toBe('cached');
-    expect(response.data?.body).toBe(`${INITIAL_DATA.data.body}:${DEFAULT_DATA}`);
+    expect(response.data?.body).toBe(`${INITIAL_DATA.data?.body}:${DEFAULT_DATA}`);
   });
 });