This is hopefully a simple example to demonstrate how to upload a file to an ESP32 using the AsyncWebServer, saving the files on to SPIFFS and having a simple upload progress bar displaced.
There are various instructions around the place, but they were all confusing and it took a long time to figure out what was needed, I hope these examples help someone.
Example-02 is more complete and offers a better user experience, with this example there is no progress of file upload after clicking the upload button.