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    yargs-parser
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    20.2.6 • Public • Published

    yargs-parser

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    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] }

    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

    Install

    npm i [email protected]

    Version

    20.2.6

    License

    ISC

    Unpacked Size

    121 kB

    Total Files

    11

    Last publish

    Collaborators

    • bcoe
    • nexdrew
    • oss-bot