When we stream a big file to the server, what is happening inside the browser? Are all the data chunks sent within a single
POST request? Or each chunk is sent by an individual
POST request and the whole file is streamed by sending multiple
No need to do multiple POSTs, the browser takes care of that for you. If you’re uploading a file you use a
<input type="file" /> HTML control and the very important
<form enctype="multipart/form-data" method="POST">
multipart/form-data attribute value on a
<form> tells the browser to split up the binary data (your file) into chunks and sent up the stream one at a time.
multipart/form-data is a MIME type and all browsers are coded to handle it as a chunked stream of binary data.
See more here in the specification: