var fs = require("fs"); var http = require("http"); var crypto = require("crypto"); function Pic(path) { var content = fs.readFileSync(path); var hash = crypto.createHash("sha1").update(content).digest("hex"); var self = { path: path, hash: hash, content: content } return self; } var currentPic = Pic("/home/martin/background.jpg"); http.createServer((req, res) => { var hash = req.url.substring(1); // Remove the first / to get only hash console.log("got hash "+hash+", existing hash is "+currentPic.hash); if (hash === currentPic.hash) { res.end(); } else { res.end(currentPic.content); } }).listen(8080);