title: Angular - How to filter day depending on month in Date of Birth
body: <p>I am using Angular-7 to develop a client portal. I want to use select option for date of birth, <strong>but year will not be inclusive</strong>. It will only have month and day. the values in the day field will depend on what month is selected. I currently have this:</p>
  
  <p>client.component.html</p>
  
  <pre><code>&lt;div class="form-group"&gt;
    &lt;label for="name"&gt;Month&lt;/label&gt;
    &lt;select class="form-control pt-1" name="month" [(ngModel)]="data.month"&gt;
      &lt;option value="1"&gt;January&lt;/option&gt;
      &lt;option value="2"&gt;February&lt;/option&gt;
      &lt;option value="3"&gt;March&lt;/option&gt;
      &lt;option value="4"&gt;April&lt;/option&gt;
      &lt;option value="5"&gt;May&lt;/option&gt;
      &lt;option value="6"&gt;June&lt;/option&gt;
      &lt;option value="7"&gt;July&lt;/option&gt;
      &lt;option value="8"&gt;August&lt;/option&gt;
      &lt;option value="9"&gt;September&lt;/option&gt;
      &lt;option value="10"&gt;October&lt;/option&gt;
      &lt;option value="11"&gt;November&lt;/option&gt;
      &lt;option value="12"&gt;December&lt;/option&gt;
    &lt;/select&gt;
  &lt;/div&gt;
  
  &lt;div class="form-group"&gt;
  &lt;label for="name"&gt;Month&lt;/label&gt;
    &lt;select class="form-control pt-1" name="day" [(ngModel)]="data.day"&gt;                
      &lt;option&gt;1&lt;/option&gt;
      &lt;option&gt;2&lt;/option&gt;
      &lt;option&gt;3&lt;/option&gt;
      &lt;option&gt;4&lt;/option&gt;
      &lt;option&gt;5&lt;/option&gt;
      &lt;option&gt;6&lt;/option&gt;
      &lt;option&gt;7&lt;/option&gt;
      &lt;option&gt;8&lt;/option&gt;
      &lt;option&gt;9&lt;/option&gt;
      &lt;option&gt;10&lt;/option&gt;
      &lt;option&gt;11&lt;/option&gt;
      &lt;option&gt;12&lt;/option&gt;
      &lt;option&gt;13&lt;/option&gt;
      &lt;option&gt;14&lt;/option&gt;
      &lt;option&gt;15&lt;/option&gt;
      &lt;option&gt;16&lt;/option&gt;
      &lt;option&gt;17&lt;/option&gt;
      &lt;option&gt;18&lt;/option&gt;
      &lt;option&gt;19&lt;/option&gt;
      &lt;option&gt;20&lt;/option&gt;
      &lt;option&gt;21&lt;/option&gt;
      &lt;option&gt;22&lt;/option&gt;
      &lt;option&gt;23&lt;/option&gt;
      &lt;option&gt;24&lt;/option&gt;
      &lt;option&gt;25&lt;/option&gt;
      &lt;option&gt;26&lt;/option&gt;
      &lt;option&gt;27&lt;/option&gt;
      &lt;option&gt;28&lt;/option&gt;
      &lt;option *ngIf="month != 'February'")&gt;
        29
      &lt;/option&gt;
      &lt;option *ngIf="month != 'February'"&gt;
        30
      &lt;/option&gt;
      &lt;option *ngIf="month == 'January' || month == 'March' || month == 'May' || month == 'July' || month == 'August' || month == 'October' || month == 'December'"&gt;
        31
      &lt;/option&gt;
   &lt;/select&gt;
  </code></pre>
  
  <p></p>
  
  <ol>
  <li><p>How do I achieve my goal?</p></li>
  <li><p>Move it into typescript (client.component.ts)</p></li>
  </ol>