yargs-parser
v5.0.1
the mighty option parser used by yargs
0/weekUpdated 8 months agoISCUnpacked: 38.5 KB
Published by Ben Coe
npm install yargs-parseryargs-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']}.{array: [{ key: 'foo', boolean: true }, {key: 'bar', number: true}]}
Indicate that keys should be parsed as an array and coerced to booleans / numbers:
.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{coerce: {foo: function (arg) {return modifiedArg}}}
(or throws an error). For arrays the function is called only once for the entire array:
.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 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 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 }
* : any new argument created by opts.default, no aliases included.boolean
* : { foo: true }
* : 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 fieldopts
of .
`js`
var parsed = parser(['--no-dice'], {
configuration: {
'boolean-negation': false
}
})
$3
* default: true.short-option-groups
* key: .
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.camel-case-expansion
* key: .
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:
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:
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:
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:
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:
Should arrays be combined when provided by both command line arguments and
a configuration file.
$3
* default: true
* key:
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:
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:
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:
Should nargs consume dash options as well as positional arguments.
$3
* default: no-
* key:
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.populate--
* key:
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.set-placeholder-key
* 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.halt-at-non-option
* key: .
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:
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:
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:
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