minargs

minargs is an argument parser with _minimal_ configuration & assumptions. Argument parsing can take many shapes but the explicit goals of this library are as follows:

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- no usage
- no validation
- no types or type cohersion
- no regular expressions
- no strictness
- no dependencies
- no information loss
- minimal assumptions
- minimal configuration
- consistant results/format
- 100% test coverage

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- Bring Your Own Usage™️
- Bring Your Own Validation™️

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``bash
npm install minargs
`

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- argv (Array)
- Default: process.argv
- The argument strings to parse

#### Options

- alias (Object)
- Default: none
- Define shorts & aliases to map to a canonical argument
- Note: only single character aliases can be parsed as "shorts" (read more in the F.A.Q. below)
- positionalValues (Boolean)
- Default: false
- Define whether or not to use positionals that follow bare flag definitions as values
- recursive (Boolean)
- Default: false
- Define whether or not to end parsing when a bare -- marker is found

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`js
{
args: {},
positionals: [],
remainder: [],
argv: []
}
`

#### args
- An Object of canonical argument keys with corresponding Array of parsed String values
- Examples:
- --foo will return [""] (note the empty string by default)
- --foo=bar will return ["bar"]
- --foo bar will return ["bar"] when positionalValues is true
- Notably, bar is treated as a positional & returned in positionals if positionalValues is false

#### positionals
- An Array of parsed positional String values

#### remainder
- An Array of String values the follow the first bare -- when recursive is false
- Notably, this is useful for recursively parsing arguments or passing along args to other processes (read more in the F.A.Q. below)

#### argv
- An Array of Objects with corresponding indexs mapping back to the original process.argv or provided Array
- Objects also contain the value parsed & type (ie. "argument", "short", "positional" or "value")
- The type "value" will only ever be defined -- in place of "positional" -- when positionalValues=true
- Notably, this is useful for recreating the original String values or extending the capabilities of this information (ref. https://github.com/pkgjs/parseargs/issues/84)

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#### Basic

`bash
$ basic.js - --foo=bar -- --baz
`

`js
#!/usr/bin/env node

// basic.js
const { minargs } = require('minargs')
const { args, positionals, remainder, argv } = minargs()

args // { "foo": ["bar"] }
positionals // ["-"]
remainder // ["--baz"]
argv // [ { index: 0, type: 'argument', value: { name: "foo", value: "bar" } } ... ]
`

#### Handling existence

Toggle Example

`bash
$ exists.js --foo
`

`js
#!/usr/bin/env node

// exists.js
const { minargs } = require('minargs')
const { args } = minargs()
if (args.foo) {
// ...
}
`


#### Handling last value define

Toggle Example

`bash
$ last-definition-.js --foo
`

`js
#!/usr/bin/env node

// exists.js
const { minargs } = require('minargs')
const { args } = minargs()
if (args.foo) {
// ...
}
`


#### Handling unknown args

Toggle Example

`bash
$ unknown.js --baz
`
#### Handling extension

`js
#!/usr/bin/env node

// unknown.js
const { minargs } = require('minargs')
const { args } = minargs()
const known = ['foo', 'bar']
const unknown = Object.keys(args).filter(arg => !known.includes(arg))
if (unknown.length > 0) {
console.error('unknown flags passed:', unknown)
// stop the process & set an exitCode appropriately
process.exit(1)
}

// ...
`


#### Handling validation

Toggle Example

`bash
$ validate.js --num=1337
`

`js
#!/usr/bin/env node

// validate.js
const { minargs } = require('minargs')
const { args } = minargs()
const usage = {
num: {
validate: (value) => {
if (!isNaN(value)) {
return Number(value)
}
throw Error('Validation error!')
}
},
force: {
validate: (value) => {
if (~['true','false'].indexOf(value.toLowerCase())) {
return Boolean(value)
}
throw Error('Validation error!')
}
}
}

Object.keys(args).filter(name => args[name]).map(name => {
usage[name].validate(args[name].pop())
})

// ...
`


#### Handling recursive parsing

Toggle Example

`bash
$ recursive-parse.js
`

`js
#!/usr/bin/env node

// recursive-parse.js
const { minargs } = require('minargs')
console.log(minargs({ recursive: true }))
// ...
`


#### Handling sub process

Toggle Example

`bash
$ mkdir.js ./path/to/new/dir/ --force --verbose --parents
`

`js
#!/usr/bin/env node

// mkdir.js
const known = ['force']
const { args, positionals } = minargs()
const cmd = (args.force) ? 'sudo mkdir' : 'mkdir'
const _args = Object.keys(flags).filter(f => known[f])

process('child_process').spawnSync(cmd, [..._args, ...positionals])
`


#### Handling robust options & usage

Toggle Example

`bash
$ usage.js -h
`

`js
#!/usr/bin/env node

// usage.js
const { minargs } = require('minargs')
const usage = {
help: {
short: 'h',
usage: 'cli --help',
description: 'Print usage information'
}
force: {
short: 'f',
usage: 'cli --force',
description: 'Run this cli tool with no restrictions'
}
}
const opts = {
alias: Object.keys(usage).filter(arg => usage[arg].short).reduce((o, k) => {
o[usage[k].short] = k
return o
}, {})
}
const { args } = minargs(opts)

if (args.help) {
Object.keys(usage).map(name => {
let short = usage[name].short ? -${usage[name].short}, : ''
let row = [ ${short}--${name}, usage[name].usage, usage[name].description]
console.log.apply(this, fill(columns, row))
})
}

/// ...
`


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#### Why isn't strictness supported?
* Strictness is a function of usage. By default, minargs does not assume anything about "known" or "unknown" arguments or their intended values (ex. defaults/types). Usage examples above show how you can quickly & easily utilize minargs as the backbone for an application which _does_ enforce strictness/validation & more.

#### Are shorts supported?
* Yes.
* Individual (ex. -a) & combined (ex. -aCdeFg) shorts are supported
* -a=b will capture & return "b" as a value
* -a b will capture & return "b" as a value if positionalValues is true

#### Are multiples supported?
* Yes.
* By default multiple definitions of the same argument will get consolidated into a single arg entry with a corresponding Array of String values
* Getting the last defined value of an argument is as simple as running .pop() on the Array (ex. args.foo.pop())

#### What is an alias?
An alias can be any other string that maps to a canonical* option; this includes single characters which will map shorts to a long-form (ex. alias: { f: foo } will parse -f as { args: { "foo": [""] } })

#### Is cmd --foo=bar baz the same as cmd baz --foo=bar?
* _Sort of_.
* The returned argv Array will change to reflect the differing positions of the arguments & positionals BUT args & positionals will remain consistent

#### Is value validation or type cohersion supported?
* No.

#### Are usage errors supported?
* No.

#### Does --no-foo coerce to --foo=false?
* No.
* --no-foo will parse to { args: { "no-foo": [""] } } & --foo-false to { args: { "no-foo": ["false"] } } respectively

#### Is --foo the same as --foo=true?
* No.
* --foo will parse to { args: { "foo": [""] } } & --foo=true to { args: { "foo": ["true"] } } respectively

#### Are environment variables supported?
* No.

#### Does -- signal the end of flags/options?
* Yes.
* Any arguments following a bare -- definition will be returned in remainder.

#### Is a value stored to represent the existence of --?
* No.
* The only way to determine if -- was present & there were arguments passed afterward is to check the value of remainder

#### Is - a positional?
* Yes.
* A bare - is treated as & returned in positionals

#### Is -bar the same as --bar?
* No.
* -bar will be parsed as short options, expanding to -b, -a, -r (ref. Utility Syntax Guidelines in POSIX.1-2017)

#### Is ---foo the same as --foo?
* No.
* ---foo returns { args: "-foo": [""] }
* --foo returns { args: { "foo": [""] }

#### Is foo=bar a positional?
* Yes.

#### Are negative numbers supported as positional values?
* No.
* minargs aligns with the POSIX Argument Syntax here (ie. "Arguments are options if they begin with a hyphen delimiter")
* --number -2 will be parsed as { args: { "number": [""], "2": [""] } }
* You will have to use explicit value setting to make this association (ex. --number=-2) & may further require validation/type coercion to determine if the value is a Number (as is shown in the usage examples above)

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minargs has a companion CLI library: @minargs/cli

#### Installation

`bash


install package globally & call bin...

npm install @minargs/cli -g && minargs

or, use npx to install & call bin...


npx -- @minargs/cli "" []
`

#### Usage

`bash
minargs "" []
`

#### Options & more....

To learn more, check out the @minargs/cli` GitHub repository or package page