app.component.ts

import { Component } from '@angular/core';

declare var TXDocumentViewer: any;

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.scss']
})

export class AppComponent {
  title = 'my-viewer-app';
  
  onTabChanged($event) {

    // the DocumentViewer doesn't exist on tab page
    if (document.getElementById("txViewer") === null) {

      if (typeof(TXDocumentViewer) !== "undefined") {
        TXDocumentViewer = undefined;
      }

    }
    else { // the DocumentViewer exists

      // wait until object TXDocumentViewer is available (lazy loading)
      var checkExist = setInterval(function() {

        if (typeof TXDocumentViewer !== "undefined") {
      
          // call init to initialize the viewer
          TXDocumentViewer.init( {
            containerID: 'txViewer',
            viewerSettings: {
              toolbarDocked: true,
              documentData: "SGVsbG8gdGhlcmU=",
              dock: "Fill",
              isSelectionActivated: true,
              showThumbnailPane: true,
              basePath: 'https://backend.textcontrol.com',
            }
          });
      
          clearInterval(checkExist);
          
        }

      }, 100); 

    }

  }
   
}