Angular2 : two way binding inside parent/child component

Question

Version: \"angular2\": \"2.0.0-beta.6\"

I would like to implement a two way binding inside a parent/child component case.

On my child component, I\'m using t

Answer 1

You can setup two-way data binding between parent and child component in the following ways:

According to Angular - Template Syntax - Two-way binding:

Angular offers a special two-way data binding syntax for this purpose, [(x)]. The [(x)] syntax combines the brackets of property binding, [x], with the parentheses of event binding, (x).

The [(x)] syntax is easy to demonstrate when the element has a settable property called x and a corresponding event named xChange.

@Input() counter: number;
@Output() counterChange = new EventEmitter();

The two-way binding syntax is really just syntactic sugar for a property binding and an event binding. Angular desugars the ChildComponent binding into this:

Example: https://stackblitz.com/edit/angular-two-way-data-binding-between-parent-and-child-component?file=src%2Fapp%2Fapp.component.ts

import { Component, Input, Output, EventEmitter } from '@angular/core';

@Component({
  selector: 'app-root',
  template: `
  

    
{{counter}}
    increment from parent
    
    
    
  
  `
})
export class AppComponent {

  counter = 0;

  increment() {
    this.counter++;
  }

  onCounterChange(counter: number) {
    this.counter = counter;
  }
}

@Component({
  selector: 'app-child',
  template: `
  

    
{{counter}}
    increment from child
  
  `,
})
export class ChildComponent {

  @Input() counter: number;
  @Output() counterChange = new EventEmitter();

  constructor() { }

  increment() {
    this.counterChange.emit(++this.counter);
  }

}