I would like to detect when Prevent Cross-site tracking is active in a browser using JavaScript.

My challenge is trying to find a method to detect this and show a warning popup to the user when this cross-site tracking is disabled by a users browser. This became essential after Safari 13 disabled it as default. I believe this might be helpful for people who are using cookies on iframes.

There are some ways such as

Check if third-party cookies are enabled

and

which are trying to bypass this security feature with using different methods and some of them are not valid anymore.

Basically what I try to achieve is from an iframe, try to detect Prevent Cross-site tracking is enabled on the browser using JavaScript.

I tried using this code:

var receiveMessage = function (evt) {
  if (evt.data === 'MM:3PCunsupported') {
    document.getElementById('result').innerHTML = 'not supported';
  } else if (evt.data === 'MM:3PCsupported') {
    document.getElementById('result').innerHTML = 'supported';
  }
};
window.addEventListener("message", receiveMessage, false);

However, this solution doesn't seem to work any more.

I would like to detect when Prevent Cross-site tracking is active in a browser using JavaScript.

My challenge is trying to find a method to detect this and show a warning popup to the user when this cross-site tracking is disabled by a users browser. This became essential after Safari 13 disabled it as default. I believe this might be helpful for people who are using cookies on iframes.

There are some ways such as

Check if third-party cookies are enabled

and

https://gist.github./iansltx/18caf551baaa60b79206

which are trying to bypass this security feature with using different methods and some of them are not valid anymore.

Basically what I try to achieve is from an iframe, try to detect Prevent Cross-site tracking is enabled on the browser using JavaScript.

I tried using this code:

var receiveMessage = function (evt) {
  if (evt.data === 'MM:3PCunsupported') {
    document.getElementById('result').innerHTML = 'not supported';
  } else if (evt.data === 'MM:3PCsupported') {
    document.getElementById('result').innerHTML = 'supported';
  }
};
window.addEventListener("message", receiveMessage, false);

However, this solution doesn't seem to work any more.

• javascript
• cookies
• safari

• did u find a solution to it ever? – Sana Commented Nov 9, 2023 at 21:31
• I don't think a pure JS solution is possible because of the nature of what you're trying to detect, either the browser gives up the info or you use the solution in Alan H's answer from the post you linked. It explains everything you'd need to know to build your own solution and there's discussion in the ments for fixing issues that have e up over the years. – Matthew Ludwig Commented Dec 10, 2024 at 6:31

1 Answer 1

You can try using Google Analytics on your site and adding code to detect if it loads. If it doesn't load, then its likely that tracker blockers are active.

Example:

<script>
var active;
</script>
<script src="https://googletagmanager./…" onerror="active = 1;"></script>
<script>
if (active !== 1) {
alert('Prevent cross site tracking is disabled');
} else {
alert("Ok")
}
</script>