angular.ts

constructor(@Inject(APP_INITIALIZER) @Optional() appInits: (() => any)[]) {
    const asyncInitPromises: Promise<any>[] = [];
    if (appInits) {
      for (let i = 0; i < appInits.length; i++) {
        const initResult = appInits[i]();
        if (isPromise(initResult)) {
          asyncInitPromises.push(initResult);
        }
      }
    }
    this._donePromise = Promise.all(asyncInitPromises).then(() => { this._done = true; });
    if (asyncInitPromises.length === 0) {
      this._done = true;
    }
  }