demo/src/app/components/+typeahead/demos/grouping/grouping.html
<pre class="card card-block card-header mb-3">Model: {{groupSelected | json}}</pre>
<input [(ngModel)]="groupSelected"
[typeahead]="statesComplex"
typeaheadOptionField="name"
typeaheadGroupField="region"
class="form-control">