demo/src/app/components/+buttons/demos/checkbox-reactiveforms/checkbox-reactiveforms.html
<pre class="card card-block card-header">{{myForm.value | json}}</pre>
<form [formGroup]="myForm">
<div class="btn-group">
<label class="btn btn-primary" [class.active]="myForm.value.left"
btnCheckbox formControlName="left"
tabindex="0" role="button">Left</label>
<label class="btn btn-primary" [class.active]="myForm.value.middle"
btnCheckbox formControlName="middle"
tabindex="0" role="button">Middle</label>
<label class="btn btn-primary" [class.active]="myForm.value.right"
btnCheckbox formControlName="right"
tabindex="0" role="button">Right</label>
</div>
</form>