meow
Advanced tools
Package description
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.
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 falseYargs 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 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 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
CLI app helper
--version--help$ npm install meow
$ ./foo-app.js unicorns --rainbow
#!/usr/bin/env node
'use strict';
const meow = require('meow');
const foo = require('.');
const cli = meow(`
Usage
$ foo <input>
Options
--rainbow, -r Include a rainbow
Examples
$ foo unicorns --rainbow
🌈 unicorns 🌈
`, {
flags: {
rainbow: {
type: 'boolean',
alias: 'r'
}
}
});
/*
{
input: ['unicorns'],
flags: {rainbow: true},
...
}
*/
foo(cli.input[0], cli.flags);
Returns an Object with:
input (Array) - Non-flag argumentsflags (Object) - Flags converted to camelCasepkg (Object) - The package.json objecthelp (string) - The help text used with --helpshowHelp([code=2]) (Function) - Show the help text and exit with codeshowVersion() (Function) - Show the version text and exitType: Object Array string
Can either be a string/array that is the help or an options object.
Type: Object
Define argument flags.
The key is the flag name and the value is an object with any of:
type: Type of value. (Possible values: string boolean)alias: Usually used to define a short flag alias.default: Default value when the flag is not specified.Example:
flags: {
unicorn: {
type: 'string',
alias: 'u',
default: 'rainbow'
}
}
Type: string boolean
Default: The package.json "description" property
Description to show above the help text.
Set it to false to disable it altogether.
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.
The description will be shown above your help text automatically.
Type: string boolean
Default: The package.json "version" property
Set a custom version output.
Type: boolean
Default: true
Automatically show the help text when the --help flag is present. Useful to set this value to false when a CLI manages child CLIs with their own help text.
Type: boolean
Default: true
Automatically show the version text when the --version flag is present. Useful to set this value to false when a CLI manages child CLIs with their own version text.
Type: Object
Default: Closest package.json upwards
package.json as an Object.
You most likely don't need this option.
Type: Array
Default: process.argv.slice(2)
Custom arguments object.
Type: boolean
Default: false
Infer the argument type.
By default, the argument 5 in $ foo 5 becomes a string. Enabling this would infer it as a number.
Type: boolean null undefined
Default: false
Value of boolean flags not defined in argv.
If set to undefined the flags not defined in argv will be excluded from the result.
The default value set in boolean flags take precedence over booleanDefault.
Example:
const cli = meow(`
Usage
$ foo
Options
--rainbow, -r Include a rainbow
--unicorn, -r Include a unicorn
Examples
$ foo
🌈 unicorns 🌈
`, {
booleanDefault: undefined,
flags: {
rainbow: {
type: 'boolean',
default: true
alias: 'r'
},
unicorn: {
type: 'boolean',
default: false
alias: 'u'
},
cake: {
type: 'boolean',
alias: 'c'
}
}
});
/*
{
flags: {rainbow: true, unicorn: false},
…
}
*/
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.
See chalk if you want to colorize the terminal output.
See get-stdin if you want to accept input from stdin.
See conf if you need to persist some data.
See update-notifier if you want update notifications.
MIT © Sindre Sorhus
FAQs
CLI app helper
We found that meow demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
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