made some changes

src/app/services/auth.service.ts

@@ -0,0 +1,33 @@
+import { Injectable } from '@angular/core';
+import { StorageService } from './storage.service';
+import { HttpService } from './http.service';
+import { Router } from '@angular/router';
+import { Observable } from 'rxjs';
+import { AuthConnstants } from '../config/auth-constants';
+
+@Injectable({
+  providedIn: 'root'
+})
+export class AuthService {
+
+  constructor(
+    private httpService: HttpService, 
+    private storageService: StorageService, 
+    private router: Router
+    ) { }
+
+    login(postData: any): Observable<any> {
+      return this.httpService.post('login', postData);
+      }
+
+      signup(postData: any): Observable<any> {
+        return this.httpService.post('signup', postData);
+        }
+
+    logout(){
+      this.storageService.removeStorageItem(AuthConnstants.AUTH).then(res =>{
+        this.router.navigate([''])
+      })
+
+    }
+}