> Progress is not an issue in any case. When we send File/Blob to worker, it reads the file chunk by chunk and responds with onProgress after each.

Yes, but I am saying that caller should maybe responsible to split data and send chunks to the worker. Wouldn't that make logic with less special cases?

> Can you explain what do you mean with createObjectURL? How would that help?

Oh, just so that when you are sending a message to the worker you do not have to serialize a large chunk of data but just send a short URL.