Pass Event from child component to parent component Angular 5

Question

I have a parent component called program-page and it has a child component called program-item now I have a button on the program-item and what I want that button to do is to call a function on the parent component.. Im not sure how I would do something like this..

program-page.component.html

<app-program-header></app-program-header>
<app-week-display></app-week-display>
<app-program-item [item]="programItem"></app-program-item>

program-page.component.ts

someFunction()

program-item.component.html

<button>click me</button> // button I want to be able to call event on parent component

Im aware I could use an event emitter but Ive never used one before and not sure how I would implement it in this case, I havent seen any examples where clicking a button on a child component calls a function on the parent

any help would be appreciated!

Answer 1

Angular has Input and Output, which can be used to provide data to a child component and send events to a parent component respectively.

You can do something like this.

program-page.component.html

<app-program-header></app-program-header>
<app-week-display></app-week-display>
<app-program-item [item]="programItem" (someEvent)="someFunction($event)"></app-program-item>

program-item.component.ts

import { EventEmitter } from '@angular/core';
....
@Output() someEvent = new EventEmitter();

program-item.component.html

<button (click)="someEvent.emit('data')">click me</button>

Primitive usage of Input and Output Stackblitz example