Download Node.js

open https://nodejs.org/download/ to download Mac OS X Install (.pkg)

install Node.js

open Terminal

$ node -h
Usage: node [options] [ -e script | script.js ] [arguments]
node debug script.js [arguments]

Options:
-v, --version print node's version
-e, --eval script evaluate script
-p, --print evaluate script and print result
-i, --interactive always enter the REPL even if stdin
does not appear to be a terminal
--no-deprecation silence deprecation warnings
--throw-deprecation throw an exception anytime a deprecated function is used
--trace-deprecation show stack traces on deprecations
--v8-options print v8 command line options
--max-stack-size=val set max v8 stack size (bytes)
--icu-data-dir=dir set ICU data load path to dir
(overrides NODE_ICU_DATA)
--enable-ssl2 enable ssl2
--enable-ssl3 enable ssl3

Environment variables:
NODE_PATH '
:'-separated list of directories
prefixed to the module search path.
NODE_MODULE_CONTEXTS Set to 1 to load modules in their own
global contexts.
NODE_DISABLE_COLORS Set to 1 to disable colors in the REPL
NODE_ICU_DATA Data path for ICU (Intl object) data

Documentation can be found at http://nodejs.org/