meow

What is meow?

The 'meow' npm package is a CLI helper that simplifies the process of writing command-line applications in Node.js. It parses arguments, generates help text, and handles errors.

What are meow's main functionalities?

Argument Parsing

Meow parses command-line arguments and options, making them easily accessible within your application.

const meow = require('meow');
const cli = meow(`
  Usage
    $ foo <input>
`);
console.log(cli.input); //=> ['inputValue']
console.log(cli.flags); //=> {flagName: flagValue}

Help Text Generation

Meow automatically generates and displays help text for your CLI application based on a template you provide.

const meow = require('meow');
const cli = meow(`
  Usage
    $ foo <input>

  Options
    --rainbow, -r  Include a rainbow
`);
// If the user runs the command with `--help`, meow will automatically display the help text.

Flags Customization

Meow allows you to define and customize flags for your CLI application, including setting aliases and default values.

const meow = require('meow');
const cli = meow(`
  Usage
    $ foo <input>
`, {
  flags: {
    rainbow: {
      type: 'boolean',
      alias: 'r'
    }
  }
});
console.log(cli.flags.rainbow); //=> true or false

Other packages similar to meow

yargs

Yargs is a powerful npm package that helps you build interactive command-line tools, by parsing arguments and generating an elegant user interface. It's more feature-rich than meow, providing a wide range of options for argument parsing, command handling, and validation.

commander

Commander is another npm package for writing command-line applications. It's similar to meow but offers a more object-oriented approach to defining commands and options. Commander is well-suited for complex CLI applications with sub-commands.

minimist

Minimist is a minimalistic argument parsing library. Unlike meow, it focuses solely on parsing command-line arguments without any additional features like help text generation or input validation.

README

meow

CLI app helper

Features

• Parses arguments using minimist
• Converts flags to camelCase
• Outputs version when --version
• Outputs description and supplied help text when --help
• Makes unhandled rejected promises fail loudly instead of the default silent fail
• Sets the process title to the binary name defined in package.json

Install

$ npm install --save meow

Usage

$ ./foo-app.js unicorns --rainbow-cake

#!/usr/bin/env node
'use strict';
const meow = require('meow');
const foo = require('./');

const cli = meow(`
	Usage
	  $ foo <input>

	Options
	  -r, --rainbow  Include a rainbow

	Examples
	  $ foo unicorns --rainbow
	  🌈 unicorns 🌈
`, {
	alias: {
		r: 'rainbow'
	}
});
/*
{
	input: ['unicorns'],
	flags: {rainbow: true},
	...
}
*/

foo(cli.input[0], cli.flags);

API

meow(options, [minimistOptions])

Returns an object with:

• input (array) - Non-flag arguments
• flags (object) - Flags converted to camelCase
• pkg (object) - The package.json object
• help (object) - The help text used with --help
• showHelp([code=0]) (function) - Show the help text and exit with code

options

Type: object, array, string

Can either be a string/array that is the help or an options object.

description

Type: string, boolean Default: The package.json "description" property

A description to show above the help text.

Set it to false to disable it altogether.

help

Type: string, boolean

The help text you want shown.

The input is reindented and starting/ending newlines are trimmed which means you can use a template literal without having to care about using the correct amount of indent.

If it's an array each item will be a line.
(Still supported, but you should use a template literal instead.)

The description will be shown above your help text automatically.

Set it to false to disable it altogether.

version

Type: string, boolean
Default: The package.json "version" property

Set a custom version output.

Set it to false to disable it altogether.

pkg

Type: string, object
Default: Closest package.json upwards

Relative path to package.json or as an object.

argv

Type: array
Default: process.argv.slice(2)

Custom arguments object.

minimistOptions

Type: object
Default: {}

Minimist options.

Keys passed to the minimist default option are decamelized, so you can for example pass in fooBar: 'baz' and have it be the default for the --foo-bar flag.

Promises

Meow will make unhandled rejected promises fail loudly instead of the default silent fail. Meaning you don't have to manually .catch() promises used in your CLI.

Tips

See chalk if you want to colorize the terminal output.

See get-stdin if you want to accept input from stdin.

See update-notifier if you want update notifications.

See configstore if you need to persist some data.

More useful CLI utilities.

License

MIT © Sindre Sorhus