yargs-parser

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 var argv = require('yargs-parser')(process.argv.slice(2)) console.log(argv)

sh node example.js --foo=33 --bar hello { _: [], foo: 33, bar: 'hello' }

or parse a string!

js var argv = require('./')('--foo=99 --bar=33') console.log(argv)

sh { _: [], foo: 99, bar: 33 }

Convert an array of mixed types before passing to yargs-parser:

js 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: indicate that keys should be parsed as an array: {array: ['foo', 'bar']}.
• opts.boolean: arguments should be parsed as booleans: {boolean: ['x', 'y']}.
• opts.config: indicate a key that represents a path to a configuration file (this file will be loaded and parsed).
• opts.coerce: provide a custom synchronous function that returns a coerced value from the argument provided (or throws an error), e.g. {coerce: {foo: function (arg) {return modifiedArg}}}.
• 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.string: keys should be treated as strings (even if they resemble a number -x 33).
• opts.configuration: provide configuration options to the yargs-parser (see: configuration).
• opts.number: keys should be treated as numbers.
• opts['--']: arguments after the end-of-options flag -- will be set to the argv.['--'] array instead of being set to the argv._ array.

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.
• 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.
• configuration: the configuration loaded from the yargs stanza in package.json.

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.

js 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?

sh node example.js -abc { _: [], a: true, b: true, c: true }

if disabled:

sh node example.js -abc { _: [], abc: true }

camel-case expansion

• default: true.
• key: camel-case-expansion.

Should hyphenated arguments be expanded into camel-case aliases?

sh node example.js --foo-bar { _: [], 'foo-bar': true, fooBar: true }

if disabled:

sh node example.js --foo-bar { _: [], 'foo-bar': true }

dot-notation

• default: true
• key: dot-notation

Should keys that contain . be treated as objects?

sh node example.js --foo.bar { _: [], foo: { bar: true } }

if disabled:

sh 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?

sh node example.js --foo=99.3 { _: [], foo: 99.3 }

if disabled:

sh 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?

sh node example.js --no-foo { _: [], foo: false }

if disabled:

sh 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:

sh node example.js -x 1 -x 2 { _: [], x: [1, 2] }

if disabled:

sh 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:

sh node example.js -x 1 2 -x 3 4 { _: [], x: [1, 2, 3, 4] }

if disabled:

sh node example.js -x 1 2 -x 3 4 { _: [], x: [[1, 2], [3, 4]] }

negation prefix

• default: no-
• key: negation-prefix

The prefix to use for negated boolean variables.

sh node example.js --no-foo { _: [], foo: false }

if set to quux:

sh node example.js --quuxfoo { _: [], foo: false }

populate --

• default: false.
• key: populate--

Should unparsed flags be stored in -- or _.

If disabled:

sh node example.js a -b -- x y { _: [ 'a', 'x', 'y' ], b: true }

If enabled:

sh node example.js a -b -- x y { _: [ 'a' ], '--': [ 'x', 'y' ], b: true }

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