I didn't know about FormData. I've been working on this PHP project for quite some time now, writing a bunch of SPA type pages writing JavaScript and PHP APIs. And never before had to use the browser so much to look at my HTTP request and responses to make sure my payloads are correct. Quite interesting how the browser packages all the input elements into a nice payload and sends it off to the server as a POST, and the format that it uses for packaging, pretty much how FormData is constructed. I was thinking the OP on this post could actually just build a JSON payload with his crop coordinates, filename, and a base64 string and post it to his API page. Then his API can just grab the payload, parse it and he would have all the data he needs to finish the image in one tidy package. But he has to start somewhere and just posting binary data to his API is a good start to get him rolling with something successful.
If it ain't broke don't fix it Discover my world at jkirkerx.com