test.js

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

declare const TXTextControl: any;

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

export class AppComponent {
  title = 'my-ds-editor-app';

  @HostListener('document:dsDocumentEditorLoaded')

  onDsDocumentEditorLoaded() {
    console.log('The TXTextControl object exists from now on.');

    TXTextControl.addEventListener("textControlLoaded", function() {
      var sel = TXTextControl.selection;
      sel.setText("Welcome to DS Server", function() {
        sel.setStart(11);
        sel.setLength(9);
        sel.setBold(true);
        sel.setFontSize(30);
      });
    });		
  }
}