title: Using tabindex between forms with typescript
body: <p>I want to implement tabbing between my input fields by using typescript. I have the following code...</p>
  
  <p>index.html</p>
  
  <pre><code>   &lt;ion-fab bottom right fab-size=60px&gt;
            &lt;button ion-fab icon-only class="btn-nav" id="down" &gt;
              &lt;ion-icon name="arrow-down"&gt;&lt;/ion-icon&gt;
            &lt;/button&gt;
            &lt;button ion-fab icon-only class="btn-nav" id="up" &gt;
              &lt;ion-icon name="arrow-up" &gt;&lt;/ion-icon&gt;
            &lt;/button&gt;
          &lt;/ion-fab&gt;
  
   &lt;form [formGroup]="itemForm" (submit)="addItem()" novalidate&gt;
      &lt;ion-row class="questions"&gt;
        &lt;ion-col col-sm-2 col-md-8&gt;
      &lt;ion-item&gt;
        &lt;ion-label stacked class="ques-title"&gt;General Name&lt;/ion-label&gt;
        &lt;ion-input formControlName="gen_name" class="input-field" type="text" tabindex="1" 
          [class.invalid]="!itemForm.controls.gen_name.valid &amp;&amp; itemForm.controls.gen_name.dirty"&gt;
        &lt;/ion-input&gt;
      &lt;/ion-item&gt;
      &lt;ion-item class="error-message" 
        *ngIf="!itemForm.controls.gen_name.valid &amp;&amp; itemForm.controls.gen_name.dirty"&gt;
        &lt;p&gt;
          Problem with the general name. No Special characters 
        &lt;/p&gt;
      &lt;/ion-item&gt;
        &lt;/ion-col&gt;
  .
  .
  .
  &lt;/form&gt;
  </code></pre>
  
  <p>index.ts</p>
  
  <pre><code> public pos: number = 0;
    public navUp: any = document.getElementById('up');
    public navDown: any = document.getElementById('down');
  
  
    setFocus () {
      document.querySelector('input[tabindex="' + this.pos +'"]').focus();
    }
  
    navUp.onclick () {
      this.pos = this.pos-1;
      this.setFocus();
    }
  
    navDown.onclick () {
      this.pos = this.pos+1;
      this.setFocus();
    }
  </code></pre>
  
  <p>But when I compile it, it shows me the following error</p>
  
  <ul>
  <li>Typescript Error Property 'focus' does not exist on type 'Element'.</li>
  <li>Typescript Error Duplicate identifier 'navUp'.</li>
  <li>Typescript Error Duplicate function implementation.</li>
  <li>Typescript Error Duplicate identifier 'navDown'.</li>
  <li>Typescript Error ';' expected.</li>
  </ul>