Basic HTTP authentication in Node.JS?

The username:password is contained in the Authorization header as a base64-encoded string.

Try this:

const http = require('http');
 
http.createServer(function (req, res) {
  var header = req.headers.authorization || '';       // get the auth header
  var token = header.split(/\s+/).pop() || '';        // and the encoded auth token
  var auth = Buffer.from(token, 'base64').toString(); // convert from base64
  var parts = auth.split(/:/);                        // split on colon
  var username = parts.shift();                       // username is first
  var password = parts.join(':');                     // everything else is the password
 
  res.writeHead(200, { 'Content-Type': 'text/plain' });
  res.end('username is "' + username + '" and password is "' + password + '"');
}).listen(1337, '127.0.0.1');

From HTTP Authentication: Basic and Digest Access Authentication – Part 2 Basic Authentication Scheme (Pages 4-5)

Basic Authentication in Backus-Naur Form

basic-credentials = base64-user-pass
base64-user-pass  = <base64 [4] encoding of user-pass,
                    except not limited to 76 char/line>
user-pass   = userid ":" password
userid      = *<TEXT excluding ":">
password    = *TEXT