What is ResumableJS?

It’s 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. This is done by splitting each files into small chunks; whenever the upload of a chunk fails, uploading is retried until the procedure completes. This allows uploads to automatically resume uploading after a network connection is lost either locally or to the server. Additionally, it allows for users to pause, resume and even recover uploads without losing state.

Resumable.js does not have any external dependencies other the HTML5 File API. This is relied on for the ability to chunk files into smaller pieces. 

Note: You also need the back-end component of ResumableJS. Be sure to also install this.