Rxjs

company.service.ts

public company$ = this.tokenService.account$
  .pipe(flatMap(account => account ? this._fetchCompany(account.companyId) : null))
  .pipe(shareReplay());

menu.component.html

<ng-template let-company ngIf="companyService.company$ | async" ngIfElse="loading">
  <div> {{ company.name }} </div>
</ng-template>

<ng-template #loading>
  <div> 資料處理中請稍候 </div>
</ng-template>

token.service.ts

public token$ = new BehaviorSubject<string>("");

public account$ = this.token$
  .pipe(map(token => this._decodeToken(token)))
  .pipe(shareReplay(1));
  
async public login(account: string, password: string) {
  let token = await this._fetchAccount(account, password);
  if (!token) throw "帳號或密碼錯誤";
  this.token$.next(token);
}

public logout () {
  this.token$.next("");
}