Error: Can't resolve 'rxjs/add/operator/ma

问题:

This is app.module.ts I have tried to done the Import of map in different project and it worked fine, but in this project it's not working.

    import { BrowserModule } from '@angular/platform-browser';
    import { NgModule } from '@angular/core';
    import {HttpModule} from '@angular/http';

    import { AppComponent } from './app.component';
    import { PagesComponent } from './pages/pages.component';

    @NgModule({
      declarations: [
        AppComponent,
        PagesComponent
      ],
      imports: [
        BrowserModule,
        HttpModule

      ],
      providers: [],
      bootstrap: [AppComponent]
    })
    export class AppModule { }

app.component.ts

import { Component } from '@angular/core';
import {PageService} from './page.service';

@Component({

  selector: 'app-root',
   templateUrl: './app.component.html',
   styleUrls: ["../assets/public/css/adminstyle.css",
            "../assets/public/css/demo.css",
          "../assets/public/css/style.css"
        ,"../assets/public/css/stylesheet.css"],
  providers:[PageService]
})
export class AppComponent {
  title = 'app';
}

page.service.ts

import {Injectable} from '@angular/core';
import {Http,Headers} from '@angular/http';

import 'rxjs/add/operator/map';

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

  constructor(private http:Http) { 
  console.log('Task Service Initialized');

  }
}

回答1:

There are some pretty heavy change in the use of rxjs 6.

Imports :

As already stated, you should now use :

import { map } from 'rxjs/operators';

(and same for other operators)

I want to mention here the other main changes :

Observable, Subject and methods that create Observables (like of) have now to be imported like that :

import { Observable, of, Subject } from 'rxjs';

You will need to use pipe to apply most operators, which might look a bit strange.

e.g. :

obs.pipe(
    map(....),
    secondOperator(....),
    thirdOperator()
)

instead of

obs.map(....)
   .secondOperator(....)
   .thirdOperator()

And finally, due to the change with pipe and conflict with JavaScript reserved words, some operators had to be renamed :

do becomes tap

catch and finally become catchError finalize

switch becomes switchAll

other functions were renamed as well :

fromPromise becomes from

throw becomes throwError

回答2:

In angular 6 import 'rxjs/add/operator/map'; become to:

import { map } from 'rxjs/operators';

Read here:https://www.academind.com/learn/javascript/rxjs-6-what-changed/