A simple JavaScript script for understanding the JavaScript runtime. It functions as a poor man's JavaScript runtime environment.

I wrote it as a way to understand how node.js works and to answer the question: is it possible to have a completely single-threaded implementation of node.js. The answer, as it turns out, is yes and the implementation is quite simple.

This script runs in Mozilla's Rhino JavaScript implementation which can be download at http://www.mozilla.org/rhino/download.html.

The code is written for clarity, not efficiency. It uses no locks and is single threaded. Don't write anything CPU intensive because even a simple setTimeout operation uses 100% CPU.

As of this first version, the interpreter quits if there are no more tasks.

Execution

At the command prompt:

$ java -jar js.jar -e "load('runtime.js'); load('lib.js'); load('example.js');"

Details

• runtime.js - contains the core event loop. Really short.
• lib.js - contains a few "libraries" built on top of the runtime.
• example.js - a few simple examples that execute in the provided runtime using the functions defined in lib.js.

License

The code is in public domain. Do what you will. As with all other Free Software licences, it comes with NO WARRANTY. Use at your own peril.