How to replace ".then" from Angularjs2 in Angularjs4 : I have an angularjs2 project where i want to update to angularjs4

     loginUser(): void {
        console.log("login.component.loginUser called");
    
        this.loginService.getTokenInfo(this.userCredentials.userName, this.userCredentials.password)
          .then(tokenInfo => this.tokenInfo = tokenInfo)
          .then(tokenInfo => myGlobals.authToken = tokenInfo.token)
          .then(() => {
            this.redirectToFuPage();
          });
      }

How do I change this to work for Angularjs4