1.8.2 • Public • Published

deprecation notice

Nomnom is deprecated. Check out, which should have most, if not all of the capability that nomnom had. Thank you!


nomnom is an option parser for node. It noms your args and gives them back to you in a hash.

var opts = require("nomnom")
   .option('debug', {
      abbr: 'd',
      flag: true,
      help: 'Print debugging info'
   .option('config', {
      abbr: 'c',
      default: 'config.json',
      help: 'JSON file with tests to run'
   .option('version', {
      flag: true,
      help: 'print version and exit',
      callback: function() {
         return "version 1.2.4";

if (opts.debug)
   // do stuff

You don't have to specify anything if you don't want to:

var opts = require("nomnom").parse();

var url = opts[0];     // get the first positional arg
var file = opts.file   // see if --file was specified
var verbose = opts.v   // see if -v was specified
var extras = opts._    // get an array of the unmatched, positional args


for node.js and npm:

npm install nomnom

More Details

Nomnom supports args like -d, --debug, --no-debug, --file=test.txt, --file test.txt, -f test.txt, -xvf, and positionals. Positionals are arguments that don't fit the -a or --atomic format and aren't attached to an option.

Values are JSON parsed, so --debug=true --count=3 --file=log.txt would give you:

   "debug": true,
   "count": 3,
   "file": "log.txt"


Nomnom supports command-based interfaces (e.g. with git: git add -p and git rebase -i where add and rebase are the commands):

var parser = require("nomnom");

   .callback(function(opts) {
   .help("run browser tests");

   .option('outfile', {
      abbr: 'o',
      help: "file to write results to"
   .option('config', {
      abbr: 'c',
      default: 'config.json',
      help: "json manifest of tests to run"
   .callback(function(opts) {
   .help("run the sanity tests")


Each command generates its own usage message when -h or --help is specified with the command.


Nomnom prints out a usage message if --help or -h is an argument. Usage for these options in test.js:

var opts = require("nomnom")
      path: {
         position: 0,
         help: "Test file to run",
         list: true
      config: {
         abbr: 'c',
         metavar: 'FILE',
         help: "Config file with tests to run"
      debug: {
         abbr: 'd',
         flag: true,
         help: "Print debugging info"

...would look like this:

usage: runtests <path>... [options]

path     Test file to run

   -c FILE, --config FILE   Config file with tests to run
   -d, --debug              Print debugging info


You can either add a specification for an option with nomnom.option('name', spec) or pass the specifications to nomnom.options() as a hash keyed on option name. Each option specification can have the following fields:

abbr and full

abbr is the single character string to match to this option, full is the full-length string (defaults to the name of the option).

This option matches -d and --debug on the command line:

nomnom.option('debug', {
   abbr: 'd'

This option matches -n 3, --num-lines 12 on the command line:

nomnom.option('numLines', {
   abbr: 'n',
   full: 'num-lines'


If this is set to true, the option acts as a flag and doesn't swallow the next value on the command line. Default is false, so normally if you had a command line --config test.js, config would get a value of test.js in the options hash. Whereas if you specify:

nomnom.option('config', {
   flag: true

config would get a value of true in the options hash, and test.js would be a free positional arg.


metavar is used in the usage printout e.g. "PATH" in "-f PATH, --file PATH".


A shorthand for abbr, full, and metavar. For example, to attach an option to -c and --config use a string: "-c FILE, --config=FILE"


A string description of the option for the usage printout.


The value to give the option if it's not specified in the arguments.


If you don't want the option JSON-parsed, specify type "string".


A callback that will be executed as soon as the option is encountered. If the callback returns a string it will print the string and exit:

nomnom.option('count', {
   callback: function(count) {
      if (count != parseInt(count)) {
         return "count must be an integer";


The position of the option if it's a positional argument. If the option should be matched to the first positional arg use position 0, etc.


Specifies that the option is a list. Appending can be achieved by specifying the arg more than once on the command line:

node test.js --file=test1.js --file=test2.js

If the option has a position and list is true, all positional args including and after position will be appended to the array.


If this is set to true and the option isn't in the args, a message will be printed and the program will exit.


A list of the possible values for the option (e.g. ['run', 'test', 'open']). If the parsed value isn't in the list a message will be printed and the program will exit.


A function that takes the value of the option as entered and returns a new value that will be seen as the value of the option.

nomnom.option('date', {
   abbr: 'd',
   transform: function(timestamp) {
     return new Date(timestamp);


Option won't be printed in the usage

Parser interface

require("nomnom") will give you the option parser. You can also make an instance of a parser with require("nomnom")(). You can chain any of these functions off of a parser:


Add an option specification with the given name:

nomnom.option('debug', {
   abbr: 'd',
   flag: true,
   help: "Print debugging info"


Add options as a hash keyed by option name, good for a cli with tons of options like this example:

   debug: {
      abbr: 'd',
      flag: true,
      help: "Print debugging info"
   fruit: {
      help: "Fruit to buy"


The string that will override the default generated usage message.


A string that is appended to the usage.


Nomnom can't detect the alias used to run your script. You can use script to provide the correct name for the usage printout instead of e.g. node test.js.


Overrides the usage printing function.


Takes a command name and gives you a command object on which you can chain command options.


Gives a command object that will be used when no command is called.


Disables coloring of the usage message.


Parses node's process.argv and returns the parsed options hash. You can also provide argv:

var opts = nomnom.parse(["-xvf", "--atomic=true"])


The same as parse().

Command interface

A command is specified with nomnom.command('name'). All these functions can be chained on a command:


Add an option specifically for this command.


Add options for this command as a hash of options keyed by name.


A callback that will be called with the parsed options when the command is used.


A help string describing the function of this command.


Override the default generated usage string for this command.

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