MemoryCache

Cache data in memory. After cacheTime, the data will be automatically deleted.

API

class MemoryCache<Key = any, Data = any> extends EventEmitter {
  static DEFAULT_CACHE_TIME: number;
  static DEFAULT_MAX_CACHE_TIME: number;
  isReady(): boolean;
  asReady(): this;
  getMaxCacheTime(): number;
  setMaxCacheTime(maxCacheTime: number): this;
  getDefaultCacheTime(): number;
  setDefaultCacheTime(defaultCacheTime: number): this;
  memorize(
    key: Key,
    data: Data,
    options?: { cacheTime?: number; cacheTimestamp?: number }
  ): this;
  set(key: Key, data: Data, options?: { cacheTime?: number }): this;
  has(key: Key): boolean;
  get(key: Key): Data | undefined;
  getCacheTime(key: Key): number | undefined;
  getCacheTimestamp(key: Key): number | undefined;
  delete(key: Key): this;
  clear(): this;
}

Statics

• DEFAULT_CACHE_TIME: Default cache time, value is 300000.
• DEFAULT_MAX_CACHE_TIME: Default max cache time, value is Number.MAX_SAFE_INTEGER. When the cacheTime is greater than or equals to the max cache time, the delete timer will no be set, which means the cache is permanent.

Events

• memoryCache.on("ready", () => {}): Ready event. MemoryCache is ready by default and this event will never be emitted. This event is mainly used when you build your own cache constructor which extends MemoryCache.
• memoryCache.on("set", (key, data) => {}): Set cache event.
• memoryCache.on("delete", (key, data) => {}): Delete cache event, including automatically delete.
• memoryCache.on("clear", () => {}): Clear event.

Events for key

• memoryCache.for(key).on("set", (data) => {}): Set cache event. The key is cache key.
• memoryCache.for(key).on("delete", (data) => {}): Delete cache event. The key is cache key.

Methods

• isReady(): Returns a boolean value indicates whether the cache is ready.
• asReady(): Make cache ready. If the cache is not ready, "ready" event will be emitted.
• getMaxCacheTime(): Get max cache time.
• setMaxCacheTime(maxCacheTime): Set max cache time.
• getDefaultCacheTime(): Get default cache time.
• setDefaultCacheTime(defaultCacheTime): Set default cache time.
• memorize(key, data[, options]): Set cache but no events emitted.
• set(key, data[, options]): Set cache and "set" events will be emitted.
• has(key): Detect whether has the cache of the specied key.
• get(key): Get cache data of the specied key. It may be undefined.
• getCacheTime(key): Get cache time.
• getCacheTimestamp(key): Returns the timestamp of the cache。
• delete(key): Delete cache manually. Invoking this method will emit "delete" events.
• clear(key): Clear all caches. It will emit "clear" event.

Example

import { MemoryCache } from "@lilib/utils";

const cache = new MemoryCache();

cache.for("user").on("set", () => {
  // Do something.
});

fetch("/users/1").then((response) => {
  cache.memorize("user", response.json());
});

fetch("/users/1", {
  method: "POST",
  body: JSON.stringify({ name: "Vincent" }),
}).then((response) => {
  cache.set("user", response.json());
});