Yargs
Yargs be a node.js library fer hearties tryin' ter parse optstrings
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## 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:
```
mocha [spec..]
Run tests with Mocha
Commands
mocha inspect [spec..] Run tests with Mocha [default]
mocha init create a client-side Mocha setup at
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]
```
* bash-completion shortcuts for commands and options.
* and [tons more](/docs/api.md).
## Installation
Stable version:
```bash
npm i yargs
```
Bleeding edge version with the most recent features:
```bash
npm i yargs@next
```
## Usage
### Simple Example
```javascript
#!/usr/bin/env node
const yargs = require('yargs/yargs')
const { hideBin } = require('yargs/helpers')
const argv = yargs(hideBin(process.argv)).argv
if (argv.ships > 3 && argv.distance < 53.5) {
console.log('Plunder more riffiwobbles!')
} else {
console.log('Retreat from the xupptumblers!')
}
```
```bash
$ ./plunder.js --ships=4 --distance=22
Plunder more riffiwobbles!
$ ./plunder.js --ships 12 --distance 98.7
Retreat from the xupptumblers!
```
> Note: `hideBin` is a shorthand for [`process.argv.slice(2)`](https://nodejs.org/en/knowledge/command-line/how-to-parse-command-line-arguments/). It has the benefit that it takes into account variations in some environments, e.g., [Electron](https://github.com/electron/electron/issues/4690).
### Complex Example
```javascript
#!/usr/bin/env node
const yargs = require('yargs/yargs')
const { hideBin } = require('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'
})
.argv
```
Run the example above with `--help` to see the help for the application.
## Supported Platforms
### TypeScript
yargs has type definitions at [@types/yargs][type-definitions].
```
npm i @types/yargs --save-dev
```
See usage examples in [docs](/docs/typescript.md).
### Deno
As of `v16`, `yargs` supports [Deno](https://github.com/denoland/deno):
```typescript
import yargs from 'https://deno.land/x/yargs/deno.ts'
import { Arguments } from 'https://deno.land/x/yargs/deno-types.ts'
yargs(Deno.args)
.command('download ', 'download a list of files', (yargs: any) => {
return yargs.positional('files', {
describe: 'a list of files to do something with'
})
}, (argv: Arguments) => {
console.info(argv)
})
.strictCommands()
.demandCommand(1)
.argv
```
### ESM
As of `v16`,`yargs` supports ESM imports:
```js
import yargs from 'yargs'
import { hideBin } from 'yargs/helpers'
yargs(hideBin(process.argv))
.command('curl ', 'fetch the contents of the URL', () => {}, (argv) => {
console.info(argv)
})
.demandCommand(1)
.argv
```
### Usage in Browser
See examples of using yargs in the browser in [docs](/docs/browser.md).
## Community
Having problems? want to contribute? join our [community slack](http://devtoolscommunity.herokuapp.com).
## Documentation
### Table of Contents
* [Yargs' API](/docs/api.md)
* [Examples](/docs/examples.md)
* [Parsing Tricks](/docs/tricks.md)
* [Stop the Parser](/docs/tricks.md#stop)
* [Negating Boolean Arguments](/docs/tricks.md#negate)
* [Numbers](/docs/tricks.md#numbers)
* [Arrays](/docs/tricks.md#arrays)
* [Objects](/docs/tricks.md#objects)
* [Quotes](/docs/tricks.md#quotes)
* [Advanced Topics](/docs/advanced.md)
* [Composing Your App Using Commands](/docs/advanced.md#commands)
* [Building Configurable CLI Apps](/docs/advanced.md#configuration)
* [Customizing Yargs' Parser](/docs/advanced.md#customizing)
* [Bundling yargs](/docs/bundling.md)
* [Contributing](/contributing.md)
## Supported Node.js Versions
Libraries in this ecosystem make a best effort to track
[Node.js' release schedule](https://nodejs.org/en/about/releases/). Here's [a
post on why we think this is important](https://medium.com/the-node-js-collection/maintainers-should-consider-following-node-js-release-schedule-ab08ed4de71a).
[npm-url]: https://www.npmjs.com/package/yargs
[npm-image]: https://img.shields.io/npm/v/yargs.svg
[standard-image]: https://img.shields.io/badge/code%20style-standard-brightgreen.svg
[standard-url]: http://standardjs.com/
[conventional-commits-image]: https://img.shields.io/badge/Conventional%20Commits-1.0.0-yellow.svg
[conventional-commits-url]: https://conventionalcommits.org/
[slack-image]: http://devtoolscommunity.herokuapp.com/badge.svg
[slack-url]: http://devtoolscommunity.herokuapp.com
[type-definitions]: https://github.com/DefinitelyTyped/DefinitelyTyped/tree/master/types/yargs
[coverage-image]: https://img.shields.io/nycrc/yargs/yargs
[coverage-url]: https://github.com/yargs/yargs/blob/master/.nycrc