Yargs be a node.js library fer hearties tryin' ter parse optstrings
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:
mocha [spec..]
Run tests with Mocha
Commands
mocha inspect [spec..] Run tests with Mocha [default]
mocha init <path> create a client-side Mocha setup at <path>
Rules & Behavior
--allow-uncaught Allow uncaught errors to propagate [boolean]
--async-only, -A Require all tests to use a callback (async) or
return a Promise [boolean]
- generate completion scripts for Bash and Zsh for your command
- and tons more.
Using npm for example:
npm i yargs#!/usr/bin/env node
import yargs from 'yargs';
import {hideBin} from 'yargs/helpers';
const argv = yargs(hideBin(process.argv)).parse();
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!Note:
hideBinis a shorthand forprocess.argv.slice(2). It has the benefit that it takes into account variations in some environments, e.g., Electron.
#!/usr/bin/env node
import yargs from 'yargs';
import {hideBin} from 'yargs/helpers';
yargs(hideBin(process.argv))
.command(
'serve [port]',
'start the server',
yargs => {
return 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',
})
.parse();Run the example above with --help to see the help for the application.
yargs has type definitions at @types/yargs.
npm i @types/yargs --save-dev
See usage examples in docs.
See examples of using yargs in the browser in docs.
Libraries in this ecosystem make a best effort to track Node.js' release schedule. Here's a post on why we think this is important.