类型'Promise<boolean | void>‘不能赋值给类型'boolean’

Question

我不明白为什么它说我不能将promise的返回值赋给布尔类型。我尝试过的任何其他方法都会告诉我，我不能将void赋给boolean类型。不知道从这里做什么

我正在尝试将checkJWT的输出赋值给promise的解析。从逻辑上讲，我可以这样做，但typescript不喜欢它。

import { Injectable } from '@angular/core';
import { HttpClient } from '@angular/common/http';


import { NotificationService } from '../index';
import { UserInterface } from '../../../models/index';

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

  constructor( 
    private notificationService: NotificationService,
    private httpClient: HttpClient
   ) { }

  checkJWT(role):boolean {
    let canVisit: boolean = this.httpClient.get(window.location.protocol + '//' + window.location.hostname + ':3000/authenticate')
    .toPromise()
    .then(
      (user: UserInterface) => { 
        return role === user.role;
    }
    ) .catch((err) => { this.notificationService })
    return canVisit;
  }

Answer 1

尝尝这个

checkJWT(role):Promise<boolean>{
    let canVisit: Promise<boolean>= <Promise<boolean>>this.httpClient.get(window.location.protocol + '//' + window.location.hostname + ':3000/authenticate')
    .toPromise()
    .then(
      (user: UserInterface) => { 
        return role === user.role;
    }
    ) .catch((err) => { this.notificationService })
    return canVisit;
  }

由于this.httpClient.get().toPromise()返回的是Promise对象