Angular没有正确加载服务：＆＃34; TypeError：无法读取属性＆＃39; logout＆＃39;未定义＆＃34;

Question

我正在通过向我的网站添加身份验证，但似乎Angular无法识别我构建的其中一项服务中的功能。

AuthService：

import { Injectable } from '@angular/core';
import { Observable, of } from 'rxjs';
import { map, catchError } from 'rxjs/operators'
import { HttpClient, HttpHeaders } from '@angular/common/http';
import { userlogon } from '../_models/userlogon';
import { User } from '../_models/User';
import { JwtHelperService } from '@auth0/angular-jwt';

const HttpOptions = {
  headers: new HttpHeaders({ "Content-type": "application/json" })
};

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

  private usersUrl= '/api/v1/accounts/';
  private logonUrl= '/api/v1/auth/login/';

  constructor(
    private http: HttpClient,
    public jwtHelper, JwtHelperService,

  ) { }

  login(username: string, password: string) {
    return this.http.post<any>(this.logonUrl, {username: username, password: password })
      .pipe(map(user => {
        if (user && user.token){
          localStorage.setItem('currentUser', JSON.stringify(user));
        }
        return user;
      }));
  }

  logout(){
    localStorage.removeItem('currentUser');
  }
}

我通过logincomponent调用它：

import { Component, OnInit } from '@angular/core';
import { FormGroup, FormBuilder, FormControl, Validators, FormArray, ReactiveFormsModule } from '@angular/forms';
import { Router, ActivatedRoute } from '@angular/router';
import { first } from 'rxjs/operators';

import { AlertService, AuthService } from '../_services';
import { Alert } from 'selenium-webdriver';

@Component({
  selector: 'app-login',
  templateUrl: './login.component.html',
  styleUrls: ['./login.component.css']
})
export class LoginComponent implements OnInit {
  returnUrl: string;
  loginForm: FormGroup;
  loading = false;
  submitted = false;

  constructor(
    private formBuilder: FormBuilder,
    private route: ActivatedRoute,
    private router: Router,
    private authenticationService: AuthService,
    private alertService: AlertService

  ) { }

  ngOnInit() {
    this.loginForm = this.formBuilder.group({
      username: ['', Validators.required],
      password: ['', Validators.required]
    });

    //reset login status
    this.authenticationService.logout();

    this.returnUrl=this.route.snapshot.queryParams['returnUrl'] || '/';
  }
  get f() {return this.loginForm.controls; }
  onSubmit(){
    console.log(this.f.username.value)
    this.submitted = true;
      // stop here if form is invalid
      if (this.loginForm.invalid) {
          return;
      }
      this.loading = true;
      this.authenticationService.login(this.f.username.value, this.f.password.value)
        .pipe(first())
        .subscribe(
          data => {
            this.router.navigate([this.returnUrl]);
          },
          error => {
            this.alertService.error(error);
            this.loading = false;
          });
  }
}

组件模板：

<div class="row">
  <div class="col-md-4 col-md-offset-4">
    <div class="well">
        <h2>Login</h2>
        <form [formGroup]="loginForm" (ngSubmit)="onSubmit()">
            <div class="form-group">
                <label for="username">Username</label>
                <input type="text" formControlName="username" class="form-control" [ngClass]="{ 'is-invalid': submitted && f.username.errors }" />
                <div *ngIf="submitted && f.username.errors" class="invalid-feedback">
                    <div *ngIf="f.username.errors.required">Username is required</div>
                </div>
            </div>
            <div class="form-group">
                <label for="password">Password</label>
                <input type="password" formControlName="password" class="form-control" [ngClass]="{ 'is-invalid': submitted && f.password.errors }" />
                <div *ngIf="submitted && f.password.errors" class="invalid-feedback">
                    <div *ngIf="f.password.errors.required">Password is required</div>
                </div>
            </div>
            <div class="form-group">
                <button [disabled]="loading" class="btn btn-primary">Login</button>
                <img *ngIf="loading" src="data:image/gif;base64,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" />
                <a [routerLink]="['/register']" class="btn btn-link">Register</a>
            </div>
        </form> 
    </div>
  </div>  
</div>

我在写作或构建内容时没有出错。但是，当我浏览到/ login页面时，我首先得到：＆＃34; ERROR TypeError：无法读取属性＆＃39; logout＆＃39;未定义＆＃34;

当发布相同但登录时。它看起来像这样：

关于可能出错的任何想法？

Answer 1

我认为问题在于您的服务，请查看此行，

constructor(
    private http: HttpClient,
    public jwtHelper: JwtHelperService //should be this
  )

Answer 2

在@Sajeetharan的帮助下解决，

constructor(
    private http: HttpClient,
    public jwtHelper, JwtHelperService,

  ) { }

错字导致错误。