An awesome list about Web Workers
Web Workers provide a simple means for web content to run scripts in background threads. The worker thread can perform tasks without interfering with the user interface.
This specification defines an API for running scripts in the background independently of any user interface scripts.
The Basics of Web Workers (Eric Bidelman - Jul 26, 2010)
Catiline.js - A JavaScript Library for workers.
Parallel.js - Library for multi-core processing in Javascript.
Using Web Workers for more responsive apps (Jason Teplitz - Oct 21, 2015)