Угловой отключение выбора выпадающего списка
Dropdown1: <select [(ngModel)]="dropdown1">
<option value="">Select</option>
<option value="1">1</option>
<option value="2">2</option>
</select>
<br/>
Dropdown2: <select [(ngModel)]="dropdown2">
<option value="">Select</option>
<option value="1">1</option>
<option value="2">2</option>
</select>
<br/>
Dropdown3: <select [(ngModel)]="dropdown3">
<option value="">Select</option>
<option value="1">1</option>
<option value="2">2</option>
</select>
<br/>
<button [disabled]="!(dropdown1 && dropdown2 && dropdown3)">Save</button>
Coding boy Hasya