How to create your command-line program (CLI) with NodeJS and Commander.js

This post will show you how to create a command-line npm module (CLI) using Commander.js module.

Commander.js is a very popular module that lets you create your own CLI program.

First, start your new project - let's say my project name is "json-now"

$ git clone https://github.com/yourname/json-now.git
$ cd json-now

Now, create your package.json file:

{
  "name": "json-now",
  "version": "0.0.1",
  "bin": {
    "json-now": "./bin/index.js"
  },
  "dependencies": {
    "commander": "^3.0.1"
  }
}

Then, install dependencies:

$ npm install

The "bin" section specifies your command line name. As you see, go ahead and create a "bin" directory with "index.js" file there:

#!/usr/bin/env node

const program = require('commander');
const ver = require('../lib/ver');
program
  .usage('[options] <file>')
  .option('-v, --version', 'show version', ver, '')
  .option('-p, --port <port>', 'use custom port')
  .option('-f, --flag', 'boolean flag', false)
  .action((file, options) => {
    console.log('file name: ', file);
    // more hanlder: require('../lib/moreHandler')(options);
  })
  .parse(process.argv);

Let's create the very first option called "-v" or " - version" which shows version number. Create a directory named "lib" and a new file "ver.js" there:

const package = require('../package.json')
module.exports = () => {
    console.log(package.version);
};

So far, it looks straight forward. You created a commander "program" which handles option like "-v" by running "ver.js"

Open Terminal and try it out:

$ node bin/index.js -v
0.0.1
$ node bin/index.js sample.json
file name: sample.json

Now, it's time to publish your command line for the world to use!

$ npm login
$ npm publish

Try out your shiny new command:
$ npm install json-now -g
$ json-now -v

The above code is located here for your reference:

https://github.com/ngduc/api-now