title: how to use *ngIf 'not equal to' for checking condition
body: <p>Is it possible to use <code>!=</code> in <code>ngIf</code>?
  I have tried but it didn't work:</p>
  
  <pre><code>&lt;div class="tranDetails tenPadding"  *ngIf="transDtlsObj?.txnHistory!='null'"&gt;
  </code></pre>