I realize this was asked a long time ago, but the other response is an incomplete answer when other tools like DropzoneJS have a way to alter the filename before it is sent to the server. After scouring the source code, it turns out that jQuery File Upload also has the ability.
In a jQuery File Upload submit event callback OR at any time before calling data.submit(), alter the files array and set uploadName. For example:
$('#fileupload').fileupload({
maxNumberOfFiles: 1,
submit: function(e, data) {
data.files[0].uploadName = 'mynewfilename.jpg';
}
});
While the name property on a browser-controlled File object is read-only, that doesn't stop new properties from being defined. jQuery File Upload sends uploadName if it exists, otherwise it falls back to name.
Of course, nothing here excludes server-side responsibilities to validate the incoming data, but it does show that it is possible to change the filename that jQuery File Upload sends to the server.