index.js

#!/usr/bin/env node

/**
 * Module dependencies.
 */
import app from './src/app.js'
import http from 'http'
import debugLogger from 'debug'
const debug = debugLogger('unboundmnl-area2-server:server')

/**
 * Port for Express application. Obtained from environment variable PORT, with a default value of 3000.
 */
const port = normalizePort(process.env.PORT || '3000')
app.set('port', port)

/**
 * HTTP server where the application runs on.
 */
const server = http.createServer(app)

/*
 * Listen on provided port, on all network interfaces.
 */
server.listen(port)
server.on('error', onError)
server.on('listening', onListening)

/**
 * Normalize a port into a number, string, or false.
 */
function normalizePort(val) {
    var port = parseInt(val, 10)

    if (isNaN(port)) {
        // named pipe
        return val
    }

    if (port >= 0) {
        // port number
        return port
    }

    return false
}

/**
 * Event listener for HTTP server "error" event.
 */
function onError(error) {
    if (error.syscall !== 'listen') {
        throw error
    }

    var bind = typeof port === 'string' ? 'Pipe ' + port : 'Port ' + port

    // handle specific listen errors with friendly messages
    switch (error.code) {
        case 'EACCES':
            console.error(bind + ' requires elevated privileges')
            process.exit(1)
            break
        case 'EADDRINUSE':
            console.error(bind + ' is already in use')
            process.exit(1)
            break
        default:
            throw error
    }
}

/**
 * Event listener for HTTP server "listening" event.
 */
function onListening() {
    var addr = server.address()
    var bind = typeof addr === 'string' ? 'pipe ' + addr : 'port ' + addr.port
    debug('Listening on ' + bind)
}