Start via
npm install
npm run build
npm start
then open http://localhost:3000 in Chromium, open DevTools,
locate input.js and set a breakpoint on line 2, go to the
Console and run testFunction() and click StepOver twice.
In the Sources panel in DevTools it will look like the execution
was paused on obj.x property access, but the Console already
shows 1 being logged and the Scope view in the sidebar shows
that the JS engine is really paused on the return position.