index.js

let http      = require('http');
let express   = require('express');
let fs        = require('fs');
let mustache  = require('mustache');

const yargs = require('yargs/yargs')
const { hideBin } = require('yargs/helpers')
const argv = yargs(hideBin(process.argv)).argv

const main = () => {
	let app       = express();
	let server    = http.createServer(app);
	let io        = require('socket.io')(server);

	let opts = {
		hostname: argv.hostname,
		port: argv.port || 1947,
		revealDir: argv.revealDir || process.cwd(),
		presentationDir: argv.presentationDir || '.',
		presentationIndex: argv.presentationIndex || '/index.html',
		pluginDir: __dirname
	};

	io.on( 'connection', socket => {

		socket.on( 'new-subscriber', data => {
			socket.broadcast.emit( 'new-subscriber', data );
		});

		socket.on( 'statechanged', data => {
			delete data.state.overview;
			socket.broadcast.emit( 'statechanged', data );
		});

		socket.on( 'statechanged-speaker', data => {
			delete data.state.overview;
			socket.broadcast.emit( 'statechanged-speaker', data );
		});

	});

	app.use( express.static( opts.revealDir ) );
	app.use( express.static( opts.presentationDir ) );

	app.get('/', ( req, res ) => {
		res.writeHead( 200, { 'Content-Type': 'text/html' } );
		fs.createReadStream( opts.presentationDir + opts.presentationIndex ).pipe( res );
	});

	app.get( '/notes/:socketId', ( req, res ) => {

		fs.readFile( opts.pluginDir + '/index.html', ( err, data ) => {
			res.send( mustache.render( data.toString(), {
				socketId : req.params.socketId
			}));
		});

	});

// Actually listen
	if(opts.hostname) {
		server.listen( opts.port || null, opts.hostname);
	} else {
		server.listen( opts.port || null);
	}

	let brown = '\033[33m',
		green = '\033[32m',
		reset = '\033[0m';

	let slidesLocation = 'http://' + (opts.hostname ? opts.hostname : 'localhost') + ( opts.port ? ( ':' + opts.port ) : '' );

	console.log( brown + 'reveal.js - Speaker Notes' + reset );
	console.log( '1. Open the slides at ' + green + slidesLocation + reset );
	console.log( `Or alternatively with QR code: ${green + slidesLocation}?qr=true${reset}`);
	console.log( '2. Click on the link in your JS console to go to the notes page' );
	console.log( '3. Advance through your slides and your notes will advance automatically' );
}

module.exports = main;