title: show json value in a label in angular 6
body: <p>In Angular 6 I click on a date time picker and set a label to the selected value.</p>
  
  <p>At the moment it is showing as <code>{ "_value": "2018-09-14T09:30:00.000Z" }</code></p>
  
  <p>How can I show only the value, 2018-09-14T09:30:00.000Z?</p>
  
  <p>Here is the html</p>
  
  <pre><code>&lt;dl-date-time-picker minuteStep="15" (change)="myDateChanged($event)"&gt;&lt;/dl-date-time-picker&gt;
  &lt;label class="text-secondary"&gt;{{ myDate | json }}&lt;/label&gt; 
  </code></pre>
  
  <p>and the called code</p>
  
  <pre><code>   myDateChanged(val: string) {
      this.myDate = JSON.stringify(val);
    }
  </code></pre>