clap

npm install clap

const cli = require('clap');

const myCommand = cli.command('my-command [optional-arg]')

    .description('Optional description')

    .version('1.2.3')

    .option('-b, --bool', 'Bollean option')

    .option('--foo <foo>', 'Option with required argument')

    .option('--bar [bar]', 'Option with optional argument')

    .option('--baz [value]', 'Option with optional argument and normalize function',

        value => Number(value),

        123 // 123 is default

    )

    .action(function({ options, args, literalArgs }) {

        // options is an object with collected values

        // args goes before options

        // literal args goes after "--"

    });

myCommand.run();  // the same as "myCommnad.run(process.argv.slice(2))"

myCommand.run(['--foo', '123', '-b'])

// sub-commands

myCommand

    .command('nested')

        .option('-q, --quz', 'Some parameter', 'Default value')

        // ...

        .end()

    .command('another-command [arg1] [arg2]')

        // ...

        .command('level3-command')

            //...

.command()

    // definition

    .description(value)

    .version(value, usage, description, action)

    .help(usage, description, action)

    .option(usage, description, ...options)

    .command(usageOrCommand)

    .extend(fn, ...options)

    .end()

    // argv processing pipeline handler setters

    .init(command, context)

    .applyConfig(context)

    .finishContext(context)

    .action(context)

    // main methods

    .parse(argv, suggest)

    .run(argv)

    // misc

    .clone(deep)

    .createOptionValues()

    .getCommand(name)

    .getCommands()

    .getOption(name)

    .getOptions()

    .outputHelp()

.option(usage, description, normalize, value)

.option(usage, description, options)

{

    default: any,          // default value

    normalize: (value, oldValue) => { ... }, // any value for option is passing through this function and its result stores as option value

    shortcut: (value, oldValue) => { ... },  // for shortcut options, the handler is executed after the value is set, and its result (an object) is used as a source of values for other options

    action: () => { ... }, // for an action option, which breaks regular args processing and preform and action (e.g. show help or version)

    config: boolean        // mark option is about config and should be applied before `applyConfig()`

}