clap

Command line argument parser

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Clap.js

A library for node.js to build command-line interfaces (CLI). With its help, making a simple CLI application is a trivial task. It equally excels in complex tools with a lot of subcommands and specific features. This library supports argument coercion and completion suggestion — typing the commands is much easier.

Inspired by commander.js

Features:

  • TBD

Usage

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')
            //...

API

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)
    .prerareContenxt(context)
    .action(context)

    // main methods
    .parse(argv, suggest)
    .run(argv)

    // misc
    .clone(deep)
    .createOptionValues()
    .getCommand(name)
    .getCommands()
    .getOption(name)
    .getOptions()
    .outputHelp()

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

There are two usage:

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

Where 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()`
}

Argv processing

  • init(command, context) // before arguments parsing
    • invoke action option and exit if any
  • apply config options
  • applyConfig(context)
  • apply all the rest options
  • prepareContext(context) // after arguments parsing
    • switch to next command -> command is prescending
      • init(command, context)
        • invoke action option and exit if any
      • apply config options
      • applyConfig(context)
      • apply all the rest options
      • prepareContext(context) // after arguments parsing
        • switch to next command
          • ...
        • action(context) -> command is target
    • action(context) -> command is target

License

MIT

If you find any bugs or have a feature request, please open an issue on github!

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