options-custom-processing.js

#!/usr/bin/env node

// This is used as an example in the README for:
//    Custom option processing
//    You may specify a function to do custom processing of option values.

const commander = require('commander');
const program = new commander.Command();

function myParseInt(value) {
  // parseInt takes a string and a radix
  const parsedValue = parseInt(value, 10);
  if (isNaN(parsedValue)) {
    throw new commander.InvalidArgumentError('Not a number.');
  }
  return parsedValue;
}

function increaseVerbosity(dummyValue, previous) {
  return previous + 1;
}

function collect(value, previous) {
  return previous.concat([value]);
}

function commaSeparatedList(value) {
  return value.split(',');
}

program
  .option('-f, --float <number>', 'float argument', parseFloat)
  .option('-i, --integer <number>', 'integer argument', myParseInt)
  .option(
    '-v, --verbose',
    'verbosity that can be increased',
    increaseVerbosity,
    0,
  )
  .option('-c, --collect <value>', 'repeatable value', collect, [])
  .option('-l, --list <items>', 'comma separated list', commaSeparatedList);

program.parse();

const options = program.opts();
if (options.float !== undefined) console.log(`float: ${options.float}`);
if (options.integer !== undefined) console.log(`integer: ${options.integer}`);
if (options.verbose > 0) console.log(`verbosity: ${options.verbose}`);
if (options.collect.length > 0) console.log(options.collect);
if (options.list !== undefined) console.log(options.list);

// Try the following:
//    node options-custom-processing -f 1e2
//    node options-custom-processing --integer 2
//    node options-custom-processing -v -v -v
//    node options-custom-processing -c a -c b -c c
//    node options-custom-processing --list x,y,z