title: Angular - Force select value to be integer
body: <pre><code>&lt;form [formGroup]="form"&gt;
      &lt;select name="area_id" formControlName="area_id"&gt;
          &lt;option value="1"&gt;Value 1&lt;/option&gt;
          &lt;option value="2"&gt;Value 2&lt;/option&gt;
          &lt;option value="3"&gt;Value 3&lt;/option&gt;
      &lt;/select&gt;
  &lt;/form&gt;
  
  &lt;pre&gt;{{ form.value | json }}&lt;/pre&gt;
  </code></pre>
  
  <p>If I select an option, the value will be string. How can I force the value to be integer?</p>