Answers for "core.js:6185 ERROR NullInjectorError: R3InjectorError(AppModule)[BookServiceService -> HttpClient -> HttpClient -> HttpClient]: NullInjectorError: No provider for HttpClient!"

angular No provider for HttpClient

// open the root app.module.ts,
import { HttpClientModule } from '@angular/common/http';

// add it to the @NgModule.imports array.
imports:[HttpClientModule,  ]

No provider for HttpClient!

import { HttpClientModule } from '@angular/common/http';