angular - Angular2, disable button if no checkbox selected

Question

I have multiple checkboxes and a button that has to be enabled only if at least one checkbox is selected

<input type="checkbox">VALUE1
<input type="checkbox">VALUE2
<input type="checkbox">VALUE3
<input type="checkbox">VALUE4
<button>Proceed</button>

How is this achieved using Angular2.

P.S: found similar questions but not using Angular2.

Answer 1

One way is to use ngModel on each checkbox, then control the button's disabled property via a method that examines each checkbox model state:

@Component({
  template: `
    <label *ngFor="let cb of checkboxes">
      <input type="checkbox" [(ngModel)]="cb.state">{{cb.label}}
    </label>
    <p><button [disabled]="buttonState()">button</button>
  `
})
class App {
  checkboxes = [{label: 'one'},{label: 'two'}];
  constructor() {}
  buttonState() {
    return !this.checkboxes.some(_ => _.state);
  }
}

Plunker