mandatory arguments with commander-js

Question

I was wondering if it is possible to create a command on commander that looks like this

toggle (on|off) <args...>

Where (on|off) means that you must choose one or the other, mandatory.

Ideally, commander should take care of throwing the appropriate error and error message.

Answer 1

This is supported from Commander version 8.

import { Command, Argument } from 'commander';
const program = new Command();

program.command('toggle')
  .addArgument(new Argument('<state>', 'toggle state').choices(['on', 'off']))
  .argument('<args...>', 'further arguments')
  .action((state, args) => {
    console.log('state:', state);
    console.log('args:', args);
  });

program.parse();

$ node index.mjs toggle purple 1 2 3
error: command-argument value 'purple' is invalid for argument 'state'. Allowed choices are on, off.
$ node index.mjs toggle on 1 2 3    
state: on
args: [ '1', '2', '3' ]
$ node index.mjs toggle --help
Usage: index toggle [options] <state> <args...>

Arguments:
  state       toggle state (choices: "on", "off")
  args        further arguments

Options:
  -h, --help  display help for command