mri 

> Quickly scan for CLI flags and arguments

This is a fast and lightweight alternative to minimist and yargs-parser.

It only exists because I find that I usually don't need most of what minimist and yargs-parser have to offer. However, mri is similar _enough_ that it might function as a "drop-in replacement" for you, too!

See Comparisons for more info.

Install

``sh
$ npm install --save mri
`

Usage

`sh
$ demo-cli --foo --bar=baz -mtv -- hello world
`

`js
const mri = require('mri');

const argv = process.argv.slice(2);

mri(argv);
//=> { _: ['hello', 'world'], foo:true, bar:'baz', m:true, t:true, v:true }

mri(argv, { boolean:['bar'] });
//=> { _: ['baz', 'hello', 'world'], foo:true, bar:true, m:true, t:true, v:true }

mri(argv, {
alias: {
b: 'bar',
foo: ['f', 'fuz']
}
});
//=> { _: ['hello', 'world'], foo:true, f:true, fuz:true, b:'baz', bar:'baz', m:true, t:true, v:true }
`

API

$3


Return: Object

#### args
Type: Array

Default: []

An array of arguments to parse. For CLI usage, send process.argv.slice(2). See process.argv for info.

#### options.alias
Type: Object

Default: {}

An object of keys whose values are Strings or Array of aliases. These will be added to the parsed output with matching values.

#### options.boolean
Type: Array|String

Default: []

A single key (or array of keys) that should be parsed as Booleans.

#### options.default
Type: Object

Default: {}

An key:value object of defaults. If a default is provided for a key, its type (typeof) will be used to cast parsed arguments.

`js
mri(['--foo', 'bar']);
//=> { _:[], foo:'bar' }

mri(['--foo', 'bar'], {
default: { foo:true, baz:'hello', bat:42 }
});
//=> { _:['bar'], foo:true, baz:'hello', bat:42 }
`

> Note: Because --foo has a default of true, its output is cast to a Boolean. This means that foo=true, making 'bar' an extra argument (_ key).

#### options.string
Type: Array|String

Default: []

A single key (or array of keys) that should be parsed as Strings.

#### options.unknown
Type: Function

Default: undefined

Callback that is run when a parsed flag has not been defined as a known key or alias. Its only parameter is the unknown flag itself; eg --foobar or -f.

Once an unknown flag is encountered, parsing will terminate, regardless of your return value.

> Note: mri _only_ checks for unknown flags if options.unknown and options.alias are populated. Otherwise, everything will be accepted.




Comparisons

#### minimist

- mri is 5x faster (see benchmarks)
- Numerical values are cast as Numbers when possible
- A key (and its aliases) will always honor opts.boolean or opts.string
- Short flag groups are treated as Booleans by default:
`js
minimist(['-abc', 'hello']);
//=> { _:[], a:'', b:'', c:'hello' }

mri(['-abc', 'hello']);
//=> { _:[], a:true, b:true, c:'hello' }
`
- The opts.unknown behaves differently:
- Unlike minimist, mri will not continue continue parsing after encountering an unknown flag
- Missing options:
- opts.stopEarly
- opts['--']
- Ignores newlines (\n) within args (see test)
- Ignores slashBreaks within args (see test)
- Ignores dot-nested flags (see test)

#### yargs-parser

- mri is 40x faster (see benchmarks)
- Numerical values are cast as Numbers when possible
- A key (and its aliases) will always honor opts.boolean or opts.string
- Missing options:
- opts.array
- opts.config
- opts.coerce
- opts.count
- opts.envPrefix
- opts.narg
- opts.normalize
- opts.configuration
- opts.number
- opts['--']
- Missing parser.detailed() method
- No additional configuration object
- Added options.unknown feature




Benchmarks

> Running Node.js v10.13.0

`
Load Times:
nopt 3.179ms
yargs-parser 2.137ms
minimist 0.746ms
mri 0.517ms

Benchmark:
minimist x 328,747 ops/sec ±1.09% (89 runs sampled)
mri x 1,622,801 ops/sec ±0.94% (92 runs sampled)
nopt x 888,223 ops/sec ±0.22% (92 runs sampled)
yargs-parser x 30,538 ops/sec ±0.81% (91 runs sampled)
``

License

MIT © Luke Edwards