Angular Universal Caching Service

httpcache.service.ts

@Injectable()
export class HttpCacheService {

  constructor(public _http: Http,
              public _cache: CacheService,
              @Inject("isNode") public isNode:boolean,
              @Inject("isBrowser") public isBrowser:boolean) { }

  get<T>(url, options?: RequestOptionsArgs, autoClear: boolean = true, browserCaching:boolean = false): Observable<T> {

    // You want to return the cache if there is a response in it.
    // This would cache the first response so if your API isn't idempotent you probably want to
    // remove the item from the cache after you use it. LRU of 1
    let key = this.createKey(url, options);

    if (this._cache.has(key)) {

      const cachedResponse = this._cache.get(key);

      // if autoClear is set to false, item will stay in cache until you manually clear it
      // ie: trigger CacheService.remove(url /* with the url/key used here */)

      if (autoClear) {
        // remove previous value automatically for now
        this._cache.remove(key);
      }
      return Observable.of(cachedResponse);
    }

    // note: you probably shouldn't .share() and you should write the correct logic
    return this._http.get(url, options)
      .map(res => res.json())
      .do(json => {
        if(this.isNode || (this.isBrowser && browserCaching)) {
          this._cache.set(key, json)
        }
      })
      .share();
  }

  createKey(url:string, options?: RequestOptionsArgs):string {
    let key = url;

    if(options && options.search) {
      let search:string;
      if(options.search instanceof URLSearchParams) {
        search = this.buildSearchParams(options.search);
      } else {
        search = options.search;
      }

      if(search) {
        key += "?" + search;
      }
    }

    return key;
  }

  buildSearchParams(search:URLSearchParams):string {
    let params:string[] = [];
    search.paramsMap.forEach((v, k) => {
      if(isUndefined(v) || isNull(v)) {
        return;
      }
      params.push(`${k}=${v}`);
    });
    return params.join('&');
  }
}