Easy Command Line Interface. In development.

Usage no npm install needed!

<script type="module">
  import easyCli from 'https://cdn.skypack.dev/easy-cli';


Easy-CLI v0.1.0 (beta)

Easy Command Line Interface NodeJS module.


  • Easy process.argv handling. Install and forget.

  • Automatically adds support for --version, --usage, etc. command line options by using package.json file and user provided simple optional settings.

  • Supports boolean values

You can learn easy-cli fast by reading basic usage below. You can see examples too: example1, example2.

Inspiration from substack/node-optimist


npm install easy-cli

Basic usage

// program.js

var easy_cli = require('easy-cli');
var cli = easy_cli();

var argv = cli.argv


// CLI.json
    // non-value options
    // i.e. --opt     => argv.opt==true
    //      --not-opt => argv.opt==false
    //      --opt abc => argv.opt==true
    "booleans": ["bool", "opt"],

    // clone values across aliases
    // i.e. argv.bool == argv.x
    //      argv.z    == argv.opt == argv.a
        "bool": "x",
        "z": ["opt", "a"]
        "z": 123,
        "a": "def"
        "bool": "Awesome boolean",

        // support for long string
        "z": "Lorem ipsum irure reprehenderit p... "
        "--opt": "Opt description",

        // support for VERY long string
        "--bool": "Lorem ipsum esse dolor mollit pariatur aliqua dolore exercitation dolor nulla quis qui in Ut esse mollit Ut veniam cupidatat est do labor... "


// package.json
    "name": "Program",
    "version": "0.1.0"


$ node program.js --version
Program 0.1.0


$ node program.js --help

             --bool, -x   Awesome boolean
          -z, --opt, -a   Lorem ipsum irure reprehenderit proident nisi labore
                          culpa adipisicing adipisicing pariatur ut eiusmod
                          dolor proident id occaecat tempor ut pariatur in
                          dolor minim nulla sint sunt do ut.
             --examples   Show code examples
             --defaults   Show default command line values
  --help, --options, -h   Show help
              --version   Show version


  z   123 [number]
  a   def [string]


   index.js --opt   Opt description
  index.js --bool   Lorem ipsum esse dolor mollit pariatur aliqua dolore
                    exercitation dolor nulla quis qui in Ut esse mollit Ut
                    veniam cupidatat est do laboris pariatur dolore eiusmod
                    elit sed ut reprehenderit exercitation ea et quis dolor
                    exercitation non amet eu in elit cillum non et magna elit
                    est elit enim amet fugiat Duis ad aute laboris elit
                    pariatur labore tempor consectetur mollit in exercitation
                    reprehenderit labore adipisicing non laboris id tempor
                    eiusmod enim irure ut ullamco non consequat dolor Excepteur
                    irure dolore laborum Ut in elit officia amet aute sit
                    proident qui dolor sunt dolor aute irure ut ad ex in aliqua
                    incididunt cillum in tempor non cupidatat pariatur labore
                    commodo eu pariatur enim reprehenderit in culpa in commodo
                    consectetur cillum mollit nisi dolore labore velit est
                    ullamco eiusmod exercitation veniam amet in cupidatat
                    ullamco proident anim ex dolore elit non do quis ex culpa
                    officia id dolor aliqua elit sed ut cupidatat consequat
                    sint enim sed mollit reprehenderit nulla cillum voluptate
                    commodo magna sit sit veniam deserunt reprehenderit est
                    mollit ex aute dolore minim sint irure ut ea Duis enim
                    fugiat dolore ad aliqua consequat deserunt ut aliqua in
                    deserunt labore do ad laborum magna officia ea laboris
                    ullamco dolore ut dolore dolor nisi in dolore minim sed
                    tempor occaecat culpa ut qui exercitation ea aute magna id
                    eiusmod officia occaecat irure reprehenderit nulla
                    consequat cillum minim occaecat commodo Duis mollit irure
                    sint fugiat voluptate eu enim sunt Excepteur anim cillum
                    deserunt exercitation incididunt elit Ut ex veniam aute ex
                    pariatur nostrud cillum laboris nisi culpa adipisicing
                    dolor enim cillum do ea adipisicing labore in laborum esse
                    elit sint eiusmod proident amet eu adipisicing mollit
                    veniam quis quis aliquip ut Ut veniam culpa et magna qui
                    reprehenderit do sint.

Easy-CLI default options

You can remove below behaviour by using easy_cli({no_defaults: true}).

You can override below behaviour by using easy_cli({show_xxx: function() { /* your stuff */ }}) where xxx is one of version,defaults,help,options,examples.


If there is package.json in the folder then

var j = require('./package.json');
console.log j.name + " " + j.version;

--options, --help

Automatically generated help using CLI.json or CLI.yaml or provided settings (see below).


Display default values from CLI.json or CLI.yaml or provided settings (see below).


Display default examples from CLI.json or CLI.yaml or provided settings (see below).





// program.js

var easy_cli = require('easy-cli');
var cli = easy_cli();

Object cli exposes the following properties:

  • [Object] cli.argv with properties cli.argv.obj and cli.argv.arr.
    • [Object] cli.argv.obj is an object that stores key, value pairs.
    • [Array] cli.argv.arr is an array that stores non-key values.


easy_cli function accepts settings object as a parameter. If there are no settings defined then easy_cli will try to load settings object from CLI.yaml or CLI.json file.

settings object can have the following properties:

  • settings.aliases
  • settings.booleans
  • settings.defaults
  • settings.examples
  • settings.descriptions
  • settings.no_defaults

settings.aliases (instanceof Object)

Maps keys into corresponding String alias|Array aliases

Aliases clone other key, value pairs (e.g. if we have y as the alias of x then -y 5 in command line will save as cli.argv.obj.x = 5 and cli.argv.obj.y = 5).


    settings.aliases = {
        x: ['y', 'z'],
        opt: 'opt2'

In the above example node program.js -x 5 and node program.js -y 5 is the same action. In other words after you define aliases you forget which key is alias and which is not alias. Aliases in cli.argv.obj are indistinguishable from their non-alias counterparts, but values are the same!.

settings.booleans (instanceof Array)

Array of keys that will be treated as booleans i.e. if a boolean key is encounter in the command line then it will be saved as cli.argv.obj. ... = true.


settings.booleans = ['asd']


$ node program.js --asd xxx

will NOT do cli.argv.obj.asd = "xxx", but cli.argv.obj.asd = true, and

$ node program.js whatever

will do cli.argv.obj.asd = false

settings.defaults (instanceof Object)

Maps keys to their default values. If key defined in settings.defaults is not in the command line then it will be stored with its default value.


settings.defaults = {
    x: 5


$ node program.js -y 7


cli.argv.obj.x == 5
cli.argv.obj.y == 7

settings.descriptions (instanceof Object)

Maps keys into their descriptions.

settings.examples (instanceof Object)

Maps command line examples into string.


settings.examples = {
    'program.js -x 7': 'example of this action'

settings.no_defaults (typeof 'bool')

If set to true then default behaviour for --version, --help, etc. is removed.

Parsing command line rules

$ node program.js option1 option2 ... optionN ... optionL
  • optionN is separated with spaces from surrounding options

  • optionL is the last option entered in command line (e.g. node program.js -a bcd --efg hij then optionL is hij).

  • optionN is parsed as following:

  • optionN that is a non-space string (e.g. abcd) or string wrapped in double quotes " (e.g. "a b c d") is considered valueN. (RegExp: /(?P<value>[^\ ]+|"[ ]+")/)

  • If optionN begins with - followed by one non--, non-space character then this character is considered keyN. (RegExp: /-(?P<key>[^-\ ])/)

  • If optionN begins with -- followed by non-empty, non-space string (e.g. --x, --xy) then this string is considered keyN. (RegExp: /--(?P<key>[^\ ]+)/)

  • If optionN begins with - followed by two or more non--, non-space characters then these characters are considered multi-boolean (see below). (RegExp: /-(?P<multiboolean>[^-\ ]+)/)

  • If all below statements are true

  • 1 < N < L

  • optionN is keyN

  • optionN+1 is valueN+1

then valueN+1 is considered a value of keyN and both are stored as cli.argv.obj.keyN = valueN+1 (e.g. -x abc --> cli.argv.obj.x = "abc").

All single characters from Multi-boolean option (see optionN definition) are treated as boolean keys except characters that have non-boolean aliases.