Setting Cookies with CORS requests
<p>I've been trying to tackle this problem for a few days. Setting cookies on CORS requests. I've seen conflicting articles and answers, some saying that as long as the XHR request has <code>withCredentials</code> set to true, and the server sends the appropriate headers, the browser should respect the <code>Set-Cookie</code> header. However, in my testing this has not been the case.</p>

<h2>Example Code:</h2>

<h3>index.js (Node.js Server)</h3>

<pre><code>const http = require('http');
const fs = require('fs');

// Pretty colors

const colors = {
  purple: '\033[95m',
  orange: '\033[93m',
  blue: '\033[97m',
  underline: '\033[4m',
  bold: '\033[1m',
  reset: '\033[0m'
}

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

  //Console logs to verify what's getting hit. 

  console.log(colors.purple + colors.underline + 'Hit it!' + colors.reset);
  console.log(colors.orange + colors.bold + 'url:' + colors.reset, req.url);

  if (/\/cookie/.test(req.url)) {
    console.log(colors.blue + 'We need to cook(ie) Jesse\n' + colors.reset);

    // Generate a random string in a rather convoluted way.
    var randomStr = Math.floor(Math.random() * Number.MAX_SAFE_INTEGER).toString(36) + 
    Math.floor(Math.random() * Number.MAX_SAFE_INTEGER).toString(36) + 
    Math.floor(Math.random() * Number.MAX_SAFE_INTEGER).toString(36);
    randomStr = new Buffer(randomStr.toString(), 'binary').toString('base64');

    // All .dev domains pointed to localhost via dnsmasq, though a hosts file
    // Update should also do the trick.
    res.writeHead(200, {
      'Set-Cookie': 'ajaxTestCookie=cookie' + randomStr + '; Domain=.example.dev; HttpOnly',
      'Access-Control-Allow-Origin': 'http://example.dev:3999',
      'Access-Control-Allow-Credentials': 'true',
      'Access-Control-Allow-Methods': 'GET, POST',
      'Access-Control-Allow-Headers': 'Content-Type, Set-Cookie, *'
    });
    return res.end('OK!');
  }

  console.log(colors.blue + 'We\'re having fun at the HTML!\n' + colors.reset);

  // Send out html file. 
  fs.readFile('./cookies.html', function (err, data) {
    if (err) {
      res.writeHead(500);
      return res.end('Failure to launch!');
    }
    res.end(data.toString());
  });
});

server.listen(3999);
</code></pre>

<h3>cookies.html</h3>

<pre><code>&lt;html&gt;

&lt;head&gt;
  &lt;title&gt;Cookie Test&lt;/title&gt;
&lt;/head&gt;

&lt;body&gt;
  &lt;button class="getCookie"&gt;Get Cookies!&lt;/button&gt;
  &lt;script&gt;
    (function() {
      document.querySelector(".getCookie").addEventListener("click", function(e) {
        console.log("test");
        var req = new XMLHttpRequest();
        req.open("GET", "http://localhost:3999/cookie", true);
        req.onload = function() {
          console.log(req.responseText);
        };
        req.withCredentials = true;
        req.send();
      });
    }());
  &lt;/script&gt;
&lt;/body&gt;

&lt;/html&gt;
</code></pre>

<p>I've tried testing this on both Firefox Developer Edition and Chrome, and the cookies will not set unless the page is accessed directly. </p>

<p>Is there anything I'm missing to get cookies working on CORS requests?</p>