index.js - Redirecting css and javascript calls

index.js

const server = http.createServer((req, res) => {

    const URL = req.url;

    if (req.url === '/') {

        // We try to read the method in a Synchronous way
        // Note that we dont assign the output to a variable,
        // instead, we store the output in the second parameter of the
        // callback function.
        fs.readFile('./views/index.html', (err, data) => {
            //  A little bit of error handling
            if (err) {
                res.writeHead(404);
                res.write('file not found');
                throw err;
            } else {
                //  We Write the headers  
                res.writeHead(200, {
                    'Content-Length': data.length,
                    'Content-Type': 'text/html',
                });
                //  We send the using the second argument in the callback function
                console.log(data);
                res.write(data);
                res.end();
            }
        });

    }
    if (URL.indexOf('.css') > 0) {
        let ext = req.url.split('.')[1];
        let file = (function () {
            let splitted = req.url.split('/');
            return splitted[splitted.length - 1];
        })()
        fs.readFile('public/' + file, (err, data) => {
            if (err) {

                res.writeHead(404)
                res.end();
                throw err
            } else {
                res.writeHead(200, {
                    'Concent-Length': data.length,
                    'Content-Type': 'text/css',
                });
                res.write(data);
                res.end();
            }
        })

    }

    if (URL.indexOf('.js') > 0) {
        fs.readFile('./public/buttons.js', (err, data) => {
            if (err) {
                res.writeHead(404);
                res.write('file not found');
                throw err;
            } else {
                res.writeHead(200, {
                    'Content-Length': data.length,
                    'Content-Type': 'text/javascript',
                });
                res.end(data);
            }

        })
    }

}).listen(PORT);