Mass File Upload Using HTML 5 and JavaScript

This page demonstrates how to upload a large number of files from a browser to a server. It works in Chrome and Firefox browsers. There are two tricks in use:

In Chrome, a file input field with webkitdirectory attribute can select a whole directory, while in Firefox, a file input field with multiple attribute can select multiple files.
The XmlHttpRequest object in JavaScript allows to select any files from the selection and upload them using HTTP POST while displaying a progress meter.

My code was inspired by How do I use Google Chrome 11's upload folder feature in my onw code ? and HTML5 FIle Upload with progress articles.

Here is the form:

Select a directory (in Chrome) or multiple files (in Firefox):