What classes should you not add to module declarations?

NgModule Declarations Array List -
We do not declare - Modules, Services, objects, and non-angular helper classes in the module's declarations. Stayed Informed - What Is Modules?

Syntax for NgModule declaration Array -

  declarations: [

    AppComponent,

    LoginComponent,

    MyPipe,

    MyDirective

  ]

The non-Angular classes and objects as following as -

1.      Strings

2.      Numbers

3.      Functions

4.      Entity Models

5.      Configurations

6.      and other helper classes

Note - You can use directives, components, and pipes classes in a module declaration.

The example of what goes into declarations array list –

//JavaScript imports directives, components, and pipes classes

import { BrowserModule } from '@angular/platform-browser';

import { NgModule } from '@angular/core';

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

import { LoginComponent } from './login/login.component';

import { MyPipe } from './my-pipe.pipe';

import { MyDirective } from './my-directive.directive';

import {MySericeService} from './my-serice.service';

import{MyModuleModule} from '../app/my-module/my-module.module';

//AppModule class with the @NgModule decorator.

@NgModule({

  declarations: [

    AppComponent,

    LoginComponent,

    MyPipe,

    MyDirective

  ],

  imports: [//DOM rendering, sanitization, and location

    BrowserModule

  ],

  providers: [//service providers

    MySericeService,

    MyModuleModule

  ],

  bootstrap: [AppComponent]  // bootstrapped entry component

})

export class AppModule {

  //exporting app module

}

You can see in the above example, I have created and declared components, directives and pipes in the @NgModule class using the CLI commands.

1.      ng g component my-component

2.      ng g pipe my-pipe

3.      ng g directive my-directive

4.      ng g service mySerice

5.      ng g module myModule

These CLI commands automatically imported components, directives, and pipes classes inside the module.