Just a dummy node CLI

dummy-cli.js

/*
 Simple and dummy CLI in node. Usage
 
 node cli.js <command> <-flags> <--options[=value]> <arguments>
 
 Example:
 
 node cli.js
 node cli.js help
 node cli.js hello
 node cli.js hello -a
 node cli.js hello --to=Someone
 node cli.js hello -a --to=Someone
*/

const argv = process.argv.slice(2);
const AVAILABLE_COMMANDS = [ 'help', 'hello' ];

const INSTRUCTION = {
  command: argv[0],
  arguments: argv.slice(1).filter(item => !item.startsWith('-')),
  flags: argv.filter(item => item.startsWith('-') && !item.startsWith('--')),
  options: argv.filter(item => item.startsWith('--')).map(item => item.split('='))
    .reduce((acc, item) => ({ ...acc, ...{[item[0]]: item[1] }}), {})
}

// ------------------------------------------------

function help() {
  console.log(`Simple Node CLI Example. Commands available

help              prints help
hello             prints hello
  -a              prints hello to all
  --to=<person>   prints hello to a given name`);
}

function hello(toAll, toPerson) {
  const and = toAll && toPerson && 'and';
  console.log(`hello ${toAll} ${and} ${toPerson}`)
}

// ------------------------------------------------

if (INSTRUCTION.command === 'help' || !AVAILABLE_COMMANDS.includes(INSTRUCTION.command)) {
  help();
}

if (INSTRUCTION.command === 'hello') {
  const toAll = INSTRUCTION.flags.includes('-a') ? 'everybody' : '';
  const toPerson = INSTRUCTION.options['--to'] || '';
  hello(toAll, toPerson);
}