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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
var 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!

var 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`:

var parse = require('yargs-parser')
parse(['-f', 11, '--zoom', 55].join(' ')) // <-- array to string
parse(['-f', 11, '--zoom', 55].map(String)) // <-- array of strings

# API

## require('yargs-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<tt>: 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<tt>: 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<tt>: provide configuration options to the yargs-parser (see: [configuration](#configuration)). *opts.count<tt>: indicate a key that should be used as a counter, e.g.,-vvv`=`{v: 3}`. *`opts.default<tt>: provide default values for keys:{default: {x: 33, y: 'hello world!'}}`. *`opts.envPrefix<tt>: environment variables (process.env<tt>) with the prefix provided should be parsed. *opts.narg<tt>: specify that a key requiresn`arguments:`{narg: {x: 2}}`. *`opts.normalize<tt>:path.normalize()`will be applied to values set to this key. *`opts.number<tt>: keys should be treated as numbers. *opts.string<tt>: 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" }

## 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' }

# 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