yargs-parser.git Source Repository

Source
https://github.com/yargs/yargs-parser.git
yargs-parser

The mighty option parser used by yargs.

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

Example
```
npm i yargs-parser --save
```
```
const argv = require('yargs-parser')(process.argv.slice(2))
console.log(argv)
```
```
$ node example.js --foo=33 --bar hello
{ _: [], foo: 33, bar: 'hello' }
```
or parse a string!
```
const argv = require('yargs-parser')('--foo=99 --bar=33')
console.log(argv)
```
```
{ _: [], foo: 99, bar: 33 }
```
Convert an array of mixed types before passing to yargs-parser:
```
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:
```
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:
```
import parser from 'yargs-parser'

const argv = parser('--foo=99 --bar=9987930', {
  string: ['bar']
})
console.log(argv)
```
Browsers:
```
<!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']}.
  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 --.
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.
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.
```
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?
```
$ node example.js -abc
{ _: [], a: true, b: true, c: true }
```
if disabled:
```
$ node example.js -abc
{ _: [], abc: true }
```
camel-case expansion
- default: true.
- key: camel-case-expansion.
Should hyphenated arguments be expanded into camel-case aliases?
```
$ node example.js --foo-bar
{ _: [], 'foo-bar': true, fooBar: true }
```
if disabled:
```
$ node example.js --foo-bar
{ _: [], 'foo-bar': true }
```
dot-notation
- default: true
- key: dot-notation
Should keys that contain . be treated as objects?
```
$ node example.js --foo.bar
{ _: [], foo: { bar: true } }
```
if disabled:
```
$ 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?
```
$ node example.js --foo=99.3
{ _: [], foo: 99.3 }
```
if disabled:
```
$ 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.
```
$ node example.js 99.3
{ _: [99.3] }
```
if disabled:
```
$ node example.js 99.3
{ _: ['99.3'] }
```
boolean negation
- default: true
- key: boolean-negation
Should variables prefixed with --no be treated as negations?
```
$ node example.js --no-foo
{ _: [], foo: false }
```
if disabled:
```
$ 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:
```
$ node example.js -x 1 -x 2
{ _: [], x: [1, 2] }
```
if disabled:
```
$ 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:
```
$ node example.js -x 1 2 -x 3 4
{ _: [], x: [1, 2, 3, 4] }
```
if disabled:
```
$ 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.
```
$ node example --arr 1 2
{ _: [], arr: [1, 2] }
```
if disabled:
```
$ 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.
```
$ node example.js --no-foo
{ _: [], foo: false }
```
if set to quux:
```
$ node example.js --quuxfoo
{ _: [], foo: false }
```
populate --
- default: false.
- key: populate--
Should unparsed flags be stored in -- or _.

If disabled:
```
$ node example.js a -b -- x y
{ _: [ 'a', 'x', 'y' ], b: true }
```
If enabled:
```
$ 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:
```
$ node example.js -a 1 -c 2
{ _: [], a: 1, c: 2 }
```
If enabled:
```
$ 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:
```
$ node example.js -a run b -x y
{ _: [ 'b' ], a: 'run', x: 'y' }
```
If enabled:
```
$ 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:
```
$ node example.js --test-field 1
{ _: [], 'test-field': 1, testField: 1, 'test-alias': 1, testAlias: 1 }
```
If enabled:
```
$ 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:
```
$ node example.js --test-field 1
{ _: [], 'test-field': 1, testField: 1 }
```
If enabled:
```
$ 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
```
$ node example.js --unknown-option --known-option 2 --string-option --unknown-option2
{ _: [], unknownOption: true, knownOption: 2, stringOption: '', unknownOption2: true }
```
If enabled
```
$ 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
Related
- maintainer
  npm
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Source

yargs-parser

Example

Deno Example

ESM Example

API

parser(args, opts={})

require('yargs-parser').detailed(args, opts={})

Configuration

short option groups

camel-case expansion

dot-notation

parse numbers

parse positional numbers

boolean negation

combine arrays

duplicate arguments array

flatten duplicate arrays

greedy arrays

nargs eats options

negation prefix

populate --

set placeholder key

halt at non-option

strip aliased

strip dashed

unknown options as args

Supported Node.js Versions

Special Thanks

License

Related

Share