cli-lit

Tool for building command-line interface (CLI) applications for Node.js

Installation

$ npm i cli-lit

Usage

Input:

#!/usr/bin/env node

import { cli } from 'cli-lit';

const prog = cli('my-cli');

prog.version('1.1.3').option('--global, -g', 'An example global flag');

prog
	.command('transform <src> <dest>')
	.describe('Transform the source file. Expects a *.js entry file.')
	.example('transform index.js out.js')
	.example('transform index.js out.js --global')
	.action((src, dest, opts) => {
		console.log(`Transforming ${src} to ${dest}`);
		console.log('↪ These are extra opts', opts);
	});

prog.parse(process.argv);

Output:

$ my-cli --help

  Usage
    $ my-cli <command> [options]

  Available Commands
    transform    Transform the source file.

  For more info, run any command with the `--help` flag
    $ my-cli transform --help

  Options
    -g, --global     An example global flag
    -v, --version    Displays current version
    -h, --help       Displays this help message

---

$ my-cli build --help

  Description
    Transform the source file.
    Expects a *.js entry file.

  Usage
    $ my-cli transform <src> <dest> [options]

  Options
    -g, --global    An example global flag
    -h, --help      Displays this help message

  Examples
    $ my-cli transform index.js out.js
    $ my-cli transform index.js out.js --global

Considerations

• Define your global/program-wide version, options, description, and/or examples first. Once you define a CLI command, you can't access the global-scope again.

• Define your commands and options in the order that you want them to appear. cli-lit will not mutate or sort your CLI for you. Global options print before local options.

• Usage text will always append [options] & --help and --version are done for you.

• Help text sections (example, options, etc) will only display if you provide values.

Subcommands

cli-lit supports subcommands out of the box. They are defined and parsed like any other command. When defining their usage, everything up until the first argument ([arg] or <arg>) is interpreted as the command string.

It is not necessary to define the subcommand's "base" as an additional command.

const prog = cli('cloud');

// This command definition is not necessary for the following subcommands
// to work. However, it's recommended that you define it first for better
// visibility.
prog
	.command('auth')
	.describe('Authenticate with the cloud service.')
	.action(opts => {
		console.log('↪️ Print available users');
	});

prog.command('auth login <name>', 'Demo...').action((name, opts) => {
	console.log(`↪️ Login user '${name}'`);
});

prog.command('auth logout <name>', 'Demo...').action((name, opts) => {
	console.log(`↪️ Logout user '${name}'`);
});

Single Command Mode

You may only need cli-lit for a single-command CLI application. To enable this, you may make use of the isSingle argument. Doing so allows you to pass the program's entire usage text into the name argument.

With "Single Command Mode" enabled, your entire binary operates as one command. This means that any prog.command calls are disallowed and will instead throw an Error.

Of course, you may still define a program version, a description, an example, and declare options. You are customizing the program's attributes as a whole.

Example

cli('serve [dir]', true)
	.version('1.0.0')
	.describe('Run a static file server')
	.example('public -qeim 31536000')
	.example('--port 8080 --etag')
	.example('my-app --dev')
	.option('-D, --dev', 'Enable "dev" mode')
	.option('-e, --etag', 'Enable "Etag" header')
	// There are a lot...
	.option('-H, --host', 'Hostname to bind', 'localhost')
	.option('-p, --port', 'Port to bind', 5000)
	.action((dir, opts) => {
		// Program handler
	})
	.parse(process.argv);

API

cli(name, isSingle)

Returns: Program

Returns your chainable cli instance, which we'll refer to as Program (or prog) in this document.

name

Type: String Required: true

The name of your Program / CLI.

isSingle

Type: Boolean Default: false

Sets the Program to Single Command Mode.

When true, this simplifies your generated --help output such that:

• the "root-level help" is your only help text
• the "root-level help" does not display an Available Commands section
• the "root-level help" does not inject $ name <command> into the Usage section
• the "root-level help" does not display For more info, run any command with the '--help' flag text

You may customize the Usage of your command by modifying the name argument directly.

Important: Whenever name includes a custom usage, then isSingle is automatically assumed and enforced!

prog.command(usage, description, options)

Creates a new Command for your Program.
All configuration methods (prog.describe, prog.action, ...) will apply to this Command until another Command has been created.

usage

Type: String

The usage pattern for your current Command. This will be included in the general or command-specific --help output.

• Required arguments are wrapped with < and > characters
• Optional arguments are wrapped with [ and ] characters

All arguments are positionally important, which means they are passed to your current Command's handler function in the order that they were defined.

Optional arguments that don't receive a value will be undefined in your handler function.

Important: You must define required arguments before optional arguments.

description

Type: String Default: ''

The Command's description. The value is passed directly to prog.describe.

options

Type: Object Default: {}

opts.alias

Type: String|Array

Optionally define one or more aliases for the current Command. When declared, the opts.alias value is passed directly to the prog.alias method.

opts.default

Type: Boolean

Manually set/force the current Command to be the Program's default command. This ensures that the current Command will run if no command was specified.

Important: If you run your Program without a Command and without specifying a default command, your Program will exit with a No command specified error.

prog.describe(text)

Add a description to the current Command.

text

Type: String|Array

The description text for the current Command. This will be included in the general or command-specific --help output.

Internally, your description will be separated into an Array of sentences.

For general --help output, only the first sentence will be displayed. However, all sentences will be printed for command-specific --help text.

prog.alias(...names)

Define one or more aliases for the current Command.

An error will be thrown if:

1. the program is in Single Command Mode or
2. prog.alias is called before any prog.command

names

Type: String

The list of aliases for the current Command. For example, you may want to define shortcuts and/or common typos for the Command's full name.

The prog.alias() is append-only, so calling it multiple times within a Command context will keep all aliases, including those initially passed via opts.alias.

prog.action(handler)

Attach a callback to the current Command.

handler

Type: Function

The function to run when the current Command is executed. Its parameters are based (positionally) on your Command's usage definition.

All options, flags, and extra/unknown values are included as the last parameter.

prog.example(string)

Add an example for the current Command.

string

Type: String

The example string to add. This will be included in the general or command-specific --help output.

Note: Your example's str will be prefixed with your Program's name.

prog.option(flags, description, value)

Add an Option to the current Command.

flags

Type: String

The Option's flags, which may optionally include an alias. You may use a comma (,) or a space ( ) to separate the flags.

description

Type: String

The description for the Option.

value

Type: String

The default value for the Option. Flags and aliases, if parsed, are true by default.

prog.version(string)

The --version and -v flags will automatically output the Program version.

string

Type: String Default: 0.0.0

The new version number for your Program.

prog.parse(argv, options)

Parse a set of CLI arguments.

argv

Type: Array

Your Program's process.argv input.

Important: You don't need to .slice(2) your process.argv input! This is done for you.

options

Type: Object Default: {}

Additional process.argv parsing config which will override any internal values.

opts.unknown

Type: Function Default: undefined

Callback to run when an unspecified option flag has been found.

Your handler will receive the unknown flag (string) as its only argument. You may return a string, which will be used as a custom error message. Otherwise, a default message is displayed.

opts.lazy

Type: Boolean Default: false

If true, your Program will not immediately execute the action handler. Instead, parse() will return an object of { name, args, handler } shape, wherein the name is the command name, args is all arguments that would be passed to the action handler, and handler is the function itself.

prog.help(command)

Manually display the help text for a given command. If no command name is provided, the general/global help is printed.

Your general and command-specific help text is automatically attached to the --help and -h flags.

Note: You don't have to call this directly! It is automatically done for you when you run bin --help

command

Type: String Default: null

The name of the command for which to display help. Otherwise displays the general help.

Development

(1) Install dependencies

$ npm i
# or
$ yarn

(2) Run initial validation

$ ./Taskfile.sh validate

(3) Start developing. See ./Taskfile.sh for more tasks to help you develop.