| # yargs-parser | |
|  | |
| [](https://www.npmjs.com/package/yargs-parser) | |
| [](https://conventionalcommits.org) | |
|  | |
| The mighty option parser used by [yargs](https://github.com/yargs/yargs). | |
| visit the [yargs website](http://yargs.js.org/) for more examples, and thorough usage instructions. | |
| <img width="250" src="https://raw.githubusercontent.com/yargs/yargs-parser/main/yargs-logo.png"> | |
| ## Example | |
| ```sh | |
| npm i yargs-parser --save | |
| ``` | |
| ```js | |
| const argv = require('yargs-parser')(process.argv.slice(2)) | |
| console.log(argv) | |
| ``` | |
| ```console | |
| $ node example.js --foo=33 --bar hello | |
| { _: [], foo: 33, bar: 'hello' } | |
| ``` | |
| _or parse a string!_ | |
| ```js | |
| const argv = require('yargs-parser')('--foo=99 --bar=33') | |
| console.log(argv) | |
| ``` | |
| ```console | |
| { _: [], foo: 99, bar: 33 } | |
| ``` | |
| Convert an array of mixed types before passing to `yargs-parser`: | |
| ```js | |
| const parse = require('yargs-parser') | |
| parse(['-f', 11, '--zoom', 55].join(' ')) // <-- array to string | |
| parse(['-f', 11, '--zoom', 55].map(String)) // <-- array of strings | |
| ``` | |
| ## Deno Example | |
| As of `v19` `yargs-parser` supports [Deno](https://github.com/denoland/deno): | |
| ```typescript | |
| import parser from "https://deno.land/x/yargs_parser/deno.ts"; | |
| const argv = parser('--foo=99 --bar=9987930', { | |
| string: ['bar'] | |
| }) | |
| console.log(argv) | |
| ``` | |
| ## ESM Example | |
| As of `v19` `yargs-parser` supports ESM (_both in Node.js and in the browser_): | |
| **Node.js:** | |
| ```js | |
| import parser from 'yargs-parser' | |
| const argv = parser('--foo=99 --bar=9987930', { | |
| string: ['bar'] | |
| }) | |
| console.log(argv) | |
| ``` | |
| **Browsers:** | |
| ```html | |
| <!doctype html> | |
| <body> | |
| <script type="module"> | |
| import parser from "https://unpkg.com/yargs-parser@19.0.0/browser.js"; | |
| const argv = parser('--foo=99 --bar=9987930', { | |
| string: ['bar'] | |
| }) | |
| console.log(argv) | |
| </script> | |
| </body> | |
| ``` | |
| ## API | |
| ### parser(args, opts={}) | |
| Parses command line arguments returning a simple mapping of keys and values. | |
| **expects:** | |
| * `args`: a string or array of strings representing the options to parse. | |
| * `opts`: provide a set of hints indicating how `args` should be parsed: | |
| * `opts.alias`: an object representing the set of aliases for a key: `{alias: {foo: ['f']}}`. | |
| * `opts.array`: indicate that keys should be parsed as an array: `{array: ['foo', 'bar']}`.<br> | |
| Indicate that keys should be parsed as an array and coerced to booleans / numbers:<br> | |
| `{array: [{ key: 'foo', boolean: true }, {key: 'bar', number: true}]}`. | |
| * `opts.boolean`: arguments should be parsed as booleans: `{boolean: ['x', 'y']}`. | |
| * `opts.coerce`: provide a custom synchronous function that returns a coerced value from the argument provided | |
| (or throws an error). For arrays the function is called only once for the entire array:<br> | |
| `{coerce: {foo: function (arg) {return modifiedArg}}}`. | |
| * `opts.config`: indicate a key that represents a path to a configuration file (this file will be loaded and parsed). | |
| * `opts.configObjects`: configuration objects to parse, their properties will be set as arguments:<br> | |
| `{configObjects: [{'x': 5, 'y': 33}, {'z': 44}]}`. | |
| * `opts.configuration`: provide configuration options to the yargs-parser (see: [configuration](#configuration)). | |
| * `opts.count`: indicate a key that should be used as a counter, e.g., `-vvv` = `{v: 3}`. | |
| * `opts.default`: provide default values for keys: `{default: {x: 33, y: 'hello world!'}}`. | |
| * `opts.envPrefix`: environment variables (`process.env`) with the prefix provided should be parsed. | |
| * `opts.narg`: specify that a key requires `n` arguments: `{narg: {x: 2}}`. | |
| * `opts.normalize`: `path.normalize()` will be applied to values set to this key. | |
| * `opts.number`: keys should be treated as numbers. | |
| * `opts.string`: keys should be treated as strings (even if they resemble a number `-x 33`). | |
| **returns:** | |
| * `obj`: an object representing the parsed value of `args` | |
| * `key/value`: key value pairs for each argument and their aliases. | |
| * `_`: an array representing the positional arguments. | |
| * [optional] `--`: an array with arguments after the end-of-options flag `--`. | |
| ### require('yargs-parser').detailed(args, opts={}) | |
| Parses a command line string, returning detailed information required by the | |
| yargs engine. | |
| **expects:** | |
| * `args`: a string or array of strings representing options to parse. | |
| * `opts`: provide a set of hints indicating how `args`, inputs are identical to `require('yargs-parser')(args, opts={})`. | |
| **returns:** | |
| * `argv`: an object representing the parsed value of `args` | |
| * `key/value`: key value pairs for each argument and their aliases. | |
| * `_`: an array representing the positional arguments. | |
| * [optional] `--`: an array with arguments after the end-of-options flag `--`. | |
| * `error`: populated with an error object if an exception occurred during parsing. | |
| * `aliases`: the inferred list of aliases built by combining lists in `opts.alias`. | |
| * `newAliases`: any new aliases added via camel-case expansion: | |
| * `boolean`: `{ fooBar: true }` | |
| * `defaulted`: any new argument created by `opts.default`, no aliases included. | |
| * `boolean`: `{ foo: true }` | |
| * `configuration`: given by default settings and `opts.configuration`. | |
| <a name="configuration"></a> | |
| ### Configuration | |
| The yargs-parser applies several automated transformations on the keys provided | |
| in `args`. These features can be turned on and off using the `configuration` field | |
| of `opts`. | |
| ```js | |
| var parsed = parser(['--no-dice'], { | |
| configuration: { | |
| 'boolean-negation': false | |
| } | |
| }) | |
| ``` | |
| ### short option groups | |
| * default: `true`. | |
| * key: `short-option-groups`. | |
| Should a group of short-options be treated as boolean flags? | |
| ```console | |
| $ node example.js -abc | |
| { _: [], a: true, b: true, c: true } | |
| ``` | |
| _if disabled:_ | |
| ```console | |
| $ node example.js -abc | |
| { _: [], abc: true } | |
| ``` | |
| ### camel-case expansion | |
| * default: `true`. | |
| * key: `camel-case-expansion`. | |
| Should hyphenated arguments be expanded into camel-case aliases? | |
| ```console | |
| $ node example.js --foo-bar | |
| { _: [], 'foo-bar': true, fooBar: true } | |
| ``` | |
| _if disabled:_ | |
| ```console | |
| $ node example.js --foo-bar | |
| { _: [], 'foo-bar': true } | |
| ``` | |
| ### dot-notation | |
| * default: `true` | |
| * key: `dot-notation` | |
| Should keys that contain `.` be treated as objects? | |
| ```console | |
| $ node example.js --foo.bar | |
| { _: [], foo: { bar: true } } | |
| ``` | |
| _if disabled:_ | |
| ```console | |
| $ node example.js --foo.bar | |
| { _: [], "foo.bar": true } | |
| ``` | |
| ### parse numbers | |
| * default: `true` | |
| * key: `parse-numbers` | |
| Should keys that look like numbers be treated as such? | |
| ```console | |
| $ node example.js --foo=99.3 | |
| { _: [], foo: 99.3 } | |
| ``` | |
| _if disabled:_ | |
| ```console | |
| $ node example.js --foo=99.3 | |
| { _: [], foo: "99.3" } | |
| ``` | |
| ### parse positional numbers | |
| * default: `true` | |
| * key: `parse-positional-numbers` | |
| Should positional keys that look like numbers be treated as such. | |
| ```console | |
| $ node example.js 99.3 | |
| { _: [99.3] } | |
| ``` | |
| _if disabled:_ | |
| ```console | |
| $ node example.js 99.3 | |
| { _: ['99.3'] } | |
| ``` | |
| ### boolean negation | |
| * default: `true` | |
| * key: `boolean-negation` | |
| Should variables prefixed with `--no` be treated as negations? | |
| ```console | |
| $ node example.js --no-foo | |
| { _: [], foo: false } | |
| ``` | |
| _if disabled:_ | |
| ```console | |
| $ node example.js --no-foo | |
| { _: [], "no-foo": true } | |
| ``` | |
| ### combine arrays | |
| * default: `false` | |
| * key: `combine-arrays` | |
| Should arrays be combined when provided by both command line arguments and | |
| a configuration file. | |
| ### duplicate arguments array | |
| * default: `true` | |
| * key: `duplicate-arguments-array` | |
| Should arguments be coerced into an array when duplicated: | |
| ```console | |
| $ node example.js -x 1 -x 2 | |
| { _: [], x: [1, 2] } | |
| ``` | |
| _if disabled:_ | |
| ```console | |
| $ node example.js -x 1 -x 2 | |
| { _: [], x: 2 } | |
| ``` | |
| ### flatten duplicate arrays | |
| * default: `true` | |
| * key: `flatten-duplicate-arrays` | |
| Should array arguments be coerced into a single array when duplicated: | |
| ```console | |
| $ node example.js -x 1 2 -x 3 4 | |
| { _: [], x: [1, 2, 3, 4] } | |
| ``` | |
| _if disabled:_ | |
| ```console | |
| $ node example.js -x 1 2 -x 3 4 | |
| { _: [], x: [[1, 2], [3, 4]] } | |
| ``` | |
| ### greedy arrays | |
| * default: `true` | |
| * key: `greedy-arrays` | |
| Should arrays consume more than one positional argument following their flag. | |
| ```console | |
| $ node example --arr 1 2 | |
| { _: [], arr: [1, 2] } | |
| ``` | |
| _if disabled:_ | |
| ```console | |
| $ node example --arr 1 2 | |
| { _: [2], arr: [1] } | |
| ``` | |
| **Note: in `v18.0.0` we are considering defaulting greedy arrays to `false`.** | |
| ### nargs eats options | |
| * default: `false` | |
| * key: `nargs-eats-options` | |
| Should nargs consume dash options as well as positional arguments. | |
| ### negation prefix | |
| * default: `no-` | |
| * key: `negation-prefix` | |
| The prefix to use for negated boolean variables. | |
| ```console | |
| $ node example.js --no-foo | |
| { _: [], foo: false } | |
| ``` | |
| _if set to `quux`:_ | |
| ```console | |
| $ node example.js --quuxfoo | |
| { _: [], foo: false } | |
| ``` | |
| ### populate -- | |
| * default: `false`. | |
| * key: `populate--` | |
| Should unparsed flags be stored in `--` or `_`. | |
| _If disabled:_ | |
| ```console | |
| $ node example.js a -b -- x y | |
| { _: [ 'a', 'x', 'y' ], b: true } | |
| ``` | |
| _If enabled:_ | |
| ```console | |
| $ node example.js a -b -- x y | |
| { _: [ 'a' ], '--': [ 'x', 'y' ], b: true } | |
| ``` | |
| ### set placeholder key | |
| * default: `false`. | |
| * key: `set-placeholder-key`. | |
| Should a placeholder be added for keys not set via the corresponding CLI argument? | |
| _If disabled:_ | |
| ```console | |
| $ node example.js -a 1 -c 2 | |
| { _: [], a: 1, c: 2 } | |
| ``` | |
| _If enabled:_ | |
| ```console | |
| $ node example.js -a 1 -c 2 | |
| { _: [], a: 1, b: undefined, c: 2 } | |
| ``` | |
| ### halt at non-option | |
| * default: `false`. | |
| * key: `halt-at-non-option`. | |
| Should parsing stop at the first positional argument? This is similar to how e.g. `ssh` parses its command line. | |
| _If disabled:_ | |
| ```console | |
| $ node example.js -a run b -x y | |
| { _: [ 'b' ], a: 'run', x: 'y' } | |
| ``` | |
| _If enabled:_ | |
| ```console | |
| $ node example.js -a run b -x y | |
| { _: [ 'b', '-x', 'y' ], a: 'run' } | |
| ``` | |
| ### strip aliased | |
| * default: `false` | |
| * key: `strip-aliased` | |
| Should aliases be removed before returning results? | |
| _If disabled:_ | |
| ```console | |
| $ node example.js --test-field 1 | |
| { _: [], 'test-field': 1, testField: 1, 'test-alias': 1, testAlias: 1 } | |
| ``` | |
| _If enabled:_ | |
| ```console | |
| $ node example.js --test-field 1 | |
| { _: [], 'test-field': 1, testField: 1 } | |
| ``` | |
| ### strip dashed | |
| * default: `false` | |
| * key: `strip-dashed` | |
| Should dashed keys be removed before returning results? This option has no effect if | |
| `camel-case-expansion` is disabled. | |
| _If disabled:_ | |
| ```console | |
| $ node example.js --test-field 1 | |
| { _: [], 'test-field': 1, testField: 1 } | |
| ``` | |
| _If enabled:_ | |
| ```console | |
| $ node example.js --test-field 1 | |
| { _: [], testField: 1 } | |
| ``` | |
| ### unknown options as args | |
| * default: `false` | |
| * key: `unknown-options-as-args` | |
| Should unknown options be treated like regular arguments? An unknown option is one that is not | |
| configured in `opts`. | |
| _If disabled_ | |
| ```console | |
| $ node example.js --unknown-option --known-option 2 --string-option --unknown-option2 | |
| { _: [], unknownOption: true, knownOption: 2, stringOption: '', unknownOption2: true } | |
| ``` | |
| _If enabled_ | |
| ```console | |
| $ node example.js --unknown-option --known-option 2 --string-option --unknown-option2 | |
| { _: ['--unknown-option'], knownOption: 2, stringOption: '--unknown-option2' } | |
| ``` | |
| ## 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). | |
| ## Special Thanks | |
| The yargs project evolves from optimist and minimist. It owes its | |
| existence to a lot of James Halliday's hard work. Thanks [substack](https://github.com/substack) **beep** **boop** \o/ | |
| ## License | |
| ISC | |