There are controls for the user to set a zoom level, but you can also defined programmatically what
the level should be, so that you have a good default. For example, in many cases you want a one-pager
to be fully visible on the screen. For that zoom="page-fit" is an excellent choice.
The component needs pdf.worker.js sometimes, depending on the PDF being loaded. It is loaded lazily by telling the component where it is and it takes care of loading the file if needed. By default, it is loaded from a CDN, '//cdnjs.cloudflare.com/ajax/libs/pdf.js/2.0.943/pdf.worker.min.js'. If you don't have internet access or don't want to rely on a server, you can download the file and deploy it within your app. When you have it available on runtime, update `worker` to point to the url for the file.