fs undefined in cakefile - node.js

Question

I'm trying to build a simple cakefile to perform build tasks for a node project I'm working on. Following this gist from github, I've managed to throw the following basic code together:
CoffeeScript = require 'coffee-script'
{exec} = require 'child_process'
fs = require 'fs'
web_build_path = 'bin/web'
task 'build', 'build server-side project code and output to bin dir', ->
makeUnrevisionedDirs()
#snip other methods...
makeUnrevisionedDirs = () ->
console.log(": adding unrevisioned directories...")
if not fs.existsSync(web_build_path)
console.log(":: adding #{web_build_path} dir")
fs.mkdirSync(web_build_path)
if not fs.existsSync('logs')
console.log(":: adding logs dir")
fs.mkdirSync('logs')
if not fs.existsSync('bin')
console.log(":: adding bin dir")
fs.mkdirSync('bin')
And get the following error, as if fs was never required:
TypeError: Cannot call method 'existsSync' of undefined
at makeUnrevisionedDirs (C:\fms\Cakefile:25:9, <js>:22:13)
at Object.makeUnrevisionedDirs [as action] (C:\fms\Cakefile:7:2, <js>:11:5)
at helpers.extend.invoke (C:\Users\Mike\AppData\Roaming\npm\node_modules\coffe
e-script\lib\coffee-script\cake.js:45:26)
at Object.exports.run (C:\Users\Mike\AppData\Roaming\npm\node_modules\coffee-s
cript\lib\coffee-script\cake.js:72:21)
at Object.<anonymous> (C:\Users\Mike\AppData\Roaming\npm\node_modules\coffee-s
cript\bin\cake:7:38)
at Module._compile (module.js:456:26)
at Object.Module._extensions..js (module.js:474:10)
at Module.load (module.js:356:32)
at Function.Module._load (module.js:312:12)
at Function.Module.runMain (module.js:497:10)
at startup (node.js:119:16)
at node.js:903:3
why is fs undefined here?

Answer 1

I had this problem and discovered I was running a really old version of node (0.6) - your require is failing quietly, fs must be a newer package that didn't exist.
In the end I installed the n package, upgraded node and all was well
How can I update Node.js and npm to the next versions?
(go right to the bottom of the answer for the 3 commands I used)
Note that I was also running Z shell and needed to tell the shell to rehash its list of executables with the rehash command before it found the newer version of node.