[whatwg] Show upload progress

[Joaquin Cuenca Abela]

Matthew wrote:
> 
> A much easier and more consistent approach would be for the browser to 
> show the upload progress itself. Complain to your friendly local 
> browser vendor.

Unfortunately such a simple approach is not good enough in this case.

The progress bar in a browser is "optimized" for small - medium file uploads: no estimated time left, quite small, on a blind corner, assumes the size of the downloaded page is somewhat in the range of the size of the file uploaded, so it's estimation of % done is wildly pessimist.

Those are all good things if you're using it to track the download of a web page that takes 5-6 seconds to download, but it's just not good enough if you know:

1) the file the user is going to upload is expected to be > 0.5M
2) once uploaded, the html with the response is extremelly small compared to the file(s) uploaded

In that use-case you want a bigger progress bar, on a very visible spot on the page, and giving the user a clue of the time remaining.