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yargs

yargs the modern, pirate-themed, successor to optimist.


Version published
Maintainers
2
Weekly downloads
86,473,093
decreased by-7.74%

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Package description

What is yargs?

The yargs npm package is a command-line argument parser that helps in building interactive command line tools, by parsing arguments and generating an elegant user interface. It provides a simple and efficient way to handle command line arguments for Node.js applications.

What are yargs's main functionalities?

Command Parsing

Yargs allows you to define commands and associated options. This feature is useful for CLI applications that perform different actions based on the command provided.

const yargs = require('yargs/yargs')(process.argv.slice(2));
yargs.command('get', 'make a get HTTP request', () => {}, (argv) => {
  console.log(`Request made to URL: ${argv.url}`);
}).argv;

Option Parsing

Yargs can parse options (also known as flags or switches) with additional configuration such as aliases, types, and descriptions.

const yargs = require('yargs/yargs')(process.argv.slice(2));
yargs.option('verbose', {
  alias: 'v',
  type: 'boolean',
  description: 'Run with verbose logging'
}).argv;

Default Values

Yargs allows setting default values for options, which will be used if no value is provided by the user.

const yargs = require('yargs/yargs')(process.argv.slice(2));
yargs.default('port', 8080).argv;

Automatic Help and Version Information

Yargs can automatically generate help and version information for the CLI tool, making it easier for users to understand how to use the application.

const yargs = require('yargs/yargs')(process.argv.slice(2));
yargs.help().version().argv;

Custom Validation

Yargs provides a way to define custom validation rules for the provided arguments, ensuring that the input meets certain criteria before the application proceeds.

const yargs = require('yargs/yargs')(process.argv.slice(2));
yargs.option('port', {
  describe: 'The port to bind on',
  demandOption: true,
  number: true
}).check((argv, options) => {
  if (argv.port < 1024) {
    throw new Error('Port must be at least 1024');
  }
  return true;
}).argv;

Other packages similar to yargs

Readme

Source

Yargs

Yargs be a node.js library fer hearties tryin' ter parse optstrings


Build Status Coverage Status NPM version js-standard-style Conventional Commits Slack

Description :

Yargs helps you build interactive command line tools, by parsing arguments and generating an elegant user interface.

It gives you:

  • commands and (grouped) options (my-program.js serve --port=5000).
  • a dynamically generated help menu based on your arguments.
  • bash-completion shortcuts for commands and options.
  • and tons more.

Installation

Stable version:

npm i yargs

Bleeding edge version with the most recent features:

npm i yargs@next

Usage :

Simple Example

#!/usr/bin/env node
const argv = require('yargs').argv

if (argv.ships > 3 && argv.distance < 53.5) {
  console.log('Plunder more riffiwobbles!')
} else {
  console.log('Retreat from the xupptumblers!')
}
$ ./plunder.js --ships=4 --distance=22
Plunder more riffiwobbles!

$ ./plunder.js --ships 12 --distance 98.7
Retreat from the xupptumblers!

Complex Example

#!/usr/bin/env node
require('yargs') // eslint-disable-line
  .command('serve [port]', 'start the server', (yargs) => {
    yargs
      .positional('port', {
        describe: 'port to bind on',
        default: 5000
      })
  }, (argv) => {
    if (argv.verbose) console.info(`start server on :${argv.port}`)
    serve(argv.port)
  })
  .option('verbose', {
    alias: 'v',
    type: 'boolean',
    description: 'Run with verbose logging'
  })
  .argv

Run the example above with --help to see the help for the application.

TypeScript

yargs has type definitions at @types/yargs.

npm i @types/yargs --save-dev

See usage examples in docs.

Community :

Having problems? want to contribute? join our community slack.

Documentation :

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Last updated on 13 Mar 2020

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