FileSaver.js is a javascript library for saving files on the client-side in all modern browsers. It is perfect for web apps that generates files on the client.
A tutorial about reading files line by line in browser using the HTML5 FileReader API and javascript.
Flow.js is a JavaScript library providing multiple simultaneous, stable, fault-tolerant and resumable/restartable file uploads via the HTML5 File API.
Resumable.js is a JavaScript library providing multiple simultaneous, stable and resumable uploads via the HTML5 File API.
The library is designed to introduce fault-tolerance into the upload of large files through HTTP. It allows for users to pause, resume and even recover uploads without losing state.
WordCount.js is a client-side JS library that counts bytes, words, lines chars, and calculates the longest line of a file. This library utilized the HTML5 File API.