A simple key value cache

key_value_cache.ts

import {interval, Subscription} from 'rxjs';
import {take} from 'rxjs/operators';
import * as cloneDeep from 'lodash.clonedeep';
import {Injectable} from '@angular/core';

export interface IStoreValue {
  _timeout?: Subscription;

  [key: string]: any;
}

@Injectable({providedIn: 'root'})
export class SimpleCacheService {

  private readonly cache = new Map<string, IStoreValue>();

  /**
   * Insert or overwrite data
   * @param key key associated with the value
   * @param value value to store
   * @param ttl Time to live in milliseconds
   */
  set(key: string, value: IStoreValue, ttl?: number) {
    value = cloneDeep(value);

    // if value already exists clear the timeout
    if (this.has(key)) {
      this.remove(key);
    }

    if (ttl) {
      // delete the value from the cache after timer times out
      value._timeout = interval(ttl)
        .pipe(take(1))
        .subscribe(this.remove.bind(this, key));
    }

    this.cache.set(key, value);

  }

  get(key: string): IStoreValue {
    return this.cache.get(key);
  }

  has(key: string) {
    return this.cache.has(key);
  }

  /**
   * Delete cached data
   * @param key item to remove
   */
  remove(key: string) {
    if (this.has(key)) {
      const cachedItem = this.get(key);

      cachedItem?._timeout.unsubscribe();
      cachedItem._timeout = null;

      return this.cache.delete(key);
    }
    return false;
  }

  /**
   * Removes all items from the cache
   */
  removeAll() {
    this.cache.forEach((value, key) => {
      this.remove(key);
    });
  }

  /**
   * Returns the cache size
   */
  size() {
    return this.cache.size;
  }

}