[Bug]: The webviewerloaded event is not fired in iframe

[uforulez]

Attach (recommended) or Link to PDF file

https://doksi.net/en/get.php?lid=40596

Web browser and its version

Firefox 133.0, Edge 131.0

Operating system and its version

Windows 11

PDF.js version

pdfjs-4.8.69-legacy-dist

Is the bug present in the latest PDF.js version?

Yes

Is a browser extension

No

Steps to reproduce the problem

The following events are fired when PDF.js is embedded in the parent page, but not fired when running in an iframe.

document.addEventListener("webviewerloaded", () => {
PDFViewerApplication.initializedPromise.then(() => {

      PDFViewerApplication.eventBus.on("documentloaded", (e) => {
        console.log("documentloaded");
      });

      PDFViewerApplication.eventBus.on("scalechanging", (e) => {
        console.log("scalechanging");
      });
    });
  });

What is the expected behavior?

I want to capture these events to track them in my Analytics software, so these events should be fired. The iframe and the parent page are in the same origin.

What went wrong?

Described above.

Link to a viewer

No response

Additional context

No response

[jonasmusall]

This is because it is fired on the parent document:

pdf.js/web/viewer.js

Lines 242 to 253 in 129fc66

	const event = new CustomEvent("webviewerloaded", {
	bubbles: true,
	cancelable: true,
	detail: {
	source: window,
	},
	});
	try {
	// Attempt to dispatch the event at the embedding `document`,
	// in order to support cases where the viewer is embedded in
	// a *dynamically* created <iframe> element.
	parent.document.dispatchEvent(event);

So you have to listen for it on the parent document as well. Either move your logic there (however then you can't access objects in the iframe), or use

parent.document.addEventListener("webviewerloaded", () => ...)