JavaScript performance is becoming more and more critical since we are all obsessed with developing CPU-hungry stuff like pixastic (manipulate image in JavaScript), Box2D.js (2D physic simulation). Sometime these computational expensive calculations will block the user from interacting with the UI and freeze the screen. So, some developer start asking for multi-threading in JavaScript.
Multi-threading is a technology that let a program split into several threads and let them run in parallel. For example the visual part including the UI is running in one thread and some other work like zipping a file is run in another thread. In that case the UI will not need to wait for the zipping process and able to respond to user input.
Sadly, this is not implemented in JavaScript (or we should say not implemented in the browsers?). But there are still some developers finding ways to simulate multi-threading. Although the tricks may not really solve the problem completely, but still are very useful to be learned. Here are two of them:
- http://www.sitepoint.com/article/multi-threading-javascript/
- http://www.dojotoolkit.org/book/dojo-book-0-9/part-5-dojox/dojox-timing
And recently, there is a threading library for Flex, which use similar techniques as above to simulate threading.