Preserve order of uploaded files (AJAX)

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I have the following question: How to preserve order of uploaded files?
I'm using AJAX upload. My goal is to either send files in order they were selected on website or get some extra information about the ordering. At first I thought I could use uploadExtraData to upload number and name as a key => value pair and the retrieve this data from $_POST, but my lack of jQuery knowledge makes this task impossible for me.
Are there any easy fixes? Possibly a JavaScript function, which inserts data about each new file?
Thank in advance