node.js beginner - why does this receive 2 responses?

Question

var http = require("http");

function onRequest(request, response) {
  console.log("Request received.");
  response.writeHead(200, {"Content-Type": "text/plain"});
  response.write("Hello World");
  response.end();
}

http.createServer(onRequest).listen(8888);

console.log("Server has started.");

this writes to console on a request from my chrome browser:

Request received Request received

Two times? Why?

Answer 1

It was your browser asking for favicon.ico