FYI, this was broken behind my company proxy. I think the proxy was rewriting the "Content-Range" request header, which is used in the function (papaparse.js:5

FYI, this was broken behind my company proxy. I think the proxy was rewriting the "Content-Range" request header, which is used in the function (papaparse.js:533): function getFileSize(xhr) { var contentRange = xhr.getResponseHeader("Content-Range"); return parseInt(contentRange.substr(contentRange.lastIndexOf("/") + 1)); } I could work around this by using the "Content-Length" header instead, which was available. Once it was working, I thought it worked quite well, with only a little bit of stuttering and visual glitches detracting from the presentation, but those are probably on my end :) I have seen a at least one similar presentations before, so I wonder if you were involved in any other similar things, or have borrowed concepts from them?