NativeScript/e2e/ui-tests-app/app/tabs/default-page.ts

import { EventData, Page, Tabs } from "@nativescript/core";

export function goToFirst(args: EventData) {
  const page = <Page>(<any>args.object).page;
  const tabsNav = <Tabs>page.getViewById("tabsNav");

  tabsNav.selectedIndex = 0;
}

export function goToSecond(args: EventData) {
  const page = <Page>(<any>args.object).page;
  const tabsNav = <Tabs>page.getViewById("tabsNav");

  tabsNav.selectedIndex = 1;
}