yargs-parser

!ci
!nycrc config on GitHub

The mighty option parser used by yargs.

visit the yargs website for more examples, and thorough usage instructions.

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:

`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




`

API

$3

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']}.

Indicate that keys should be parsed as an array and coerced to booleans / numbers:

{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:

{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:

{configObjects: [{'x': 5, 'y': 33}, {'z': 44}]}.
* opts.configuration: provide configuration options to the yargs-parser (see: 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 --.

$3

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.

$3

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
}
})
`

$3

* 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 }
`

$3

* 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 }
`

$3

* 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 }
`

$3

* 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" }
`

$3

* 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'] }
`

$3

* 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 }
`

$3

* default: false
* key: combine-arrays

Should arrays be combined when provided by both command line arguments and
a configuration file.

$3

* 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 }
`

$3

* 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]] }
`

$3

* 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.

$3

* default: false
* key: nargs-eats-options

Should nargs consume dash options as well as positional arguments.

$3

* 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 }
`

$3

* 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 }
`

$3

* 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 }
`

$3

* 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' }
`

$3

* 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 }
`

$3

* 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 }
`

$3

* 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. Here's a
post on why we think this is important.

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 beep boop \o/

License

ISC