2023-10-03 11:14:36 +08:00
# yargs-parser
[](https://www.npmjs.com/package/yargs-parser)
[](https://conventionalcommits.org)
The mighty option parser used by [yargs ](https://github.com/yargs/yargs ).
visit the [yargs website ](http://yargs.js.org/ ) for more examples, and thorough usage instructions.
< img width = "250" src = "https://raw.githubusercontent.com/yargs/yargs-parser/main/yargs-logo.png" >
## 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 ](https://github.com/denoland/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
<!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']}` .< br >
Indicate that keys should be parsed as an array and coerced to booleans / numbers:< br >
`{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:< br >
`{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:< br >
`{configObjects: [{'x': 5, 'y': 33}, {'z': 44}]}` .
* `opts.configuration` : provide configuration options to the yargs-parser (see: [configuration ](#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` .
< a name = "configuration" > < / a >
### 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?
```console
$ node example.js -abc
{ _: [], a: true, b: true, c: true }
```
_if disabled:_
```console
$ node example.js -abc
{ _: [], abc: true }
```
### camel-case expansion
* default: `true` .
* key: `camel-case-expansion` .
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 }
```
### dot-notation
* default: `true`
* key: `dot-notation`
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 }
```
### parse numbers
* default: `true`
* key: `parse-numbers`
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" }
```
### parse positional numbers
* default: `true`
* key: `parse-positional-numbers`
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'] }
```
### boolean negation
* default: `true`
* key: `boolean-negation`
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 }
```
### 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:
```console
$ node example.js -x 1 -x 2
{ _: [], x: [1, 2] }
```
_if disabled:_
```console
$ 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:
```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]] }
```
### greedy arrays
* default: `true`
* key: `greedy-arrays`
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` .**
### 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.
```console
$ node example.js --no-foo
{ _: [], foo: false }
```
_if set to `quux` :_
```console
$ node example.js --quuxfoo
{ _: [], foo: false }
```
### populate --
* default: `false` .
* key: `populate--`
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 }
```
### 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:_
```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 }
```
### 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:_
```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' }
```
### strip aliased
* default: `false`
* key: `strip-aliased`
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 }
```
### 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:_
```console
$ node example.js --test-field 1
{ _: [], 'test-field': 1, testField: 1 }
```
_If enabled:_
```console
$ 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_
```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 ](https://nodejs.org/en/about/releases/ ). Here's [a
post on why we think this is important](https://medium.com/the-node-js-collection/maintainers-should-consider-following-node-js-release-schedule-ab08ed4de71a).
## 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 ](https://github.com/substack ) **beep** **boop** \o/
## License
ISC
