Third party viewer usage

The default viewer is built on the display layer and is the UI for PDF viewer in Firefox and the other browser extensions within the project. It can be a good starting point for building your own viewer. However, we do ask if you plan to embed the viewer in your own site, that it not just be an unmodified version. Please re-skin it or build upon it.

Initialization promise

For custom deployments it is often useful to know when the viewer is fully initialized. Previously this was possible by listening to the localized event, but since pull request #11607 there is a simpler way:

document.addEventListener("webviewerloaded", function() {
  PDFViewerApplication.initializedPromise.then(function() {
    // The viewer has now been initialized.
  })
});