simple node.js web server

here is node.js code that functions as a basic web server.

to run the code, place it on the IFS, in a file named simpleServer.js

call qp2term
-- start node:
export QIBM_MULTI_THREADED=Y
/QOpenSys/QIBM/ProdData/OPS/Node6/bin/nodever.sh 6

-- then run node to start the node web server:
cd /home/xxx
node simpleServer.js

the code uses async/await to check for the existence of a file.

// using async/await to check for the existance of a file:
const exist = await fs_exists(fs, pathname) ;
if (!exist)
{
// if the file is not found, return 404
res.statusCode = 404;
res.end(`File ${pathname} not found!`);
return;
}

// compared to traditional way of using a callback:
fs.exists(pathname, function (exist)
{
if (!exist)
{
// if the file is not found, return 404
res.statusCode = 404;
res.end(`File ${pathname} not found!`);
return;
}

-----------------

// /home/njs/simpleServer.js

// simpleServer.js - basic web server. Serves back the files requested in
the
// url. use async and await.

const http = require('http');
const url = require('url');
const fs = require('fs');
const path = require('path');
const port = process.argv[2] || 8080;

const webServer = http.createServer( async (req, res) =>
{
console.log(`${req.method} ${req.url}`);

// special file name. Shutdown this process.
if (req.url == '/shutdown')
{
webServer.close();
process.exitCode = 1;
process.exit(1);
return;
}

// parse URL
const parsedUrl = url.parse(req.url);
// extract URL path
let pathname = `.${parsedUrl.pathname}`;
// based on the URL path, extract the file extention. e.g. .js, .doc, ...
const ext = path.parse(pathname).ext;
// maps file extention to MIME typere
const map = {
'.ico': 'image/x-icon',
'.html': 'text/html',
'.js': 'text/javascript',
'.json': 'application/json',
'.css': 'text/css',
'.png': 'image/png',
'.jpg': 'image/jpeg',
'.wav': 'audio/wav',
'.mp3': 'audio/mpeg',
'.svg': 'image/svg+xml',
'.pdf': 'application/pdf',
'.doc': 'application/msword'
};

const exist = await fs_exists(fs, pathname) ;
if (!exist)
{
// if the file is not found, return 404
res.statusCode = 404;
res.end(`File ${pathname} not found!`);
return;
}

// if is a directory search for index file matching the extention
if (fs.statSync(pathname).isDirectory()) pathname += '/index' + ext;

// read file from file system
fs.readFile(pathname, function (err, data)
{
if (err)
{
res.statusCode = 500;
res.end(`Error getting the file: ${err}.`);
} else
{
// if the file is found, set Content-type and send data
res.setHeader('Content-type', map[ext] || 'text/plain');
res.end(data);
}
});

}).listen(parseInt(port));

console.log(`Server listening on port ${port}`);

// ------------------------ fs_exists ------------------------------
function fs_exists( fs, pathname )
{
const promise = new Promise( (resolve, reject) =>
{
fs.exists(pathname, function (exist)
{
resolve( exist ) ;
}) ;
}) ;
return promise ;
}