how to use parent module component in child module component in angular2

Question

I have header that should be used in both child and parent module.that was imported and used in parent module but when try to import and using in child component it showing erro

Answer 1

You should create a shared module with the components you want to use, export these components, and import the shared module in your other modules (parent and child for your case).

Shared module:

import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { SharedComponent1 } from "./SharedComponent1";
import { SharedComponent2 } from "./SharedComponent2";

@NgModule({
imports: [
    CommonModule
],
declarations: [
    SharedComponent1,
    SharedComponent2
],
exports: [
    SharedComponent1,
    SharedComponent2
]
})
export class SharedModule {}

Using Shared module:

import { NgModule }       from '@angular/core';
import { CommonModule }   from '@angular/common';
...
import { SharedModule } from './SharedModule';

@NgModule({
imports: [
    CommonModule,
    ...
    SharedModule
],
declarations: [
    ...
],
providers: [
    ...
]
})
export class AppModule{}