streamming from browser

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 POST requests?

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">

The 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.