defaultCommand.js

#!/usr/bin/env node

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

// Example program using the command configuration option isDefault to specify the default command.

program
  .command('build')
  .description('build web site for deployment')
  .action(() => {
    console.log('build');
  });

program
  .command('deploy')
  .description('deploy web site to production')
  .action(() => {
    console.log('deploy');
  });

program
  .command('serve', { isDefault: true })
  .description('launch web server')
  .option('-p,--port <port_number>', 'web port')
  .action((options) => {
    console.log(`server on port ${options.port}`);
  });

program.parse(process.argv);

// Try the following:
//    node defaultCommand.js build
//    node defaultCommand.js serve -p 8080
//    node defaultCommand.js -p 443