Device ID on google tag manager

Question

I have a question about the possibility of assigning an id to a device (pc, mobile or tablet).

I would like to assign a unique device ID to a single device in order to track its path on my website. My site does not require registration and login so I cannot use the classic UserID.

I should integrate it with a variable on Google Tag Manager and then it should be written in Javascript.

Can anyone help me?

Answer 1

Even I guess the original GA client id is already what you are chasing for. You can take a look about it first.

But here still have the option to do your own device id:

1. You can create a Tag first in Google Tag Manager

type : Custom JavaScript

Don't add the trigger yet. We will get back to this.

<script>
  (function(){
    function setCookie(name,value,days) {
      var expires = "";
      if (days) {
        var date = new Date();
        date.setTime(date.getTime() + (days*24*60*60*1000));
        expires = "; expires=" + date.toUTCString();
      }
      document.cookie = name + "=" + (value || "")  + expires + "; path=/";
    }
    function getCookie(name) {
      var nameEQ = name + "=";
      var ca = document.cookie.split(';');
      for(var i=0;i < ca.length;i++) {
        var c = ca[i];
        while (c.charAt(0)==' ') c = c.substring(1,c.length);
        if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
      }
      return null;
    }
    function eraseCookie(name) {   
      document.cookie = name +'=; Path=/; Expires=Thu, 01 Jan 1970 00:00:01 GMT;';
    }

    // From another stack overflow answer https://stackoverflow.com/questions/14573223/set-cookie-and-get-cookie-with-javascript
function uuidv4() {
  return ([1e7] + -1e3 + -4e3 + -8e3 + -1e11).replace(/[018]/g, c => (c ^ crypto.getRandomValues(new Uint8Array(1))[0] & 15 >> c / 4).toString(16));
}

    var deviceIdCookie = getCookie("self_device_id");
    if(!deviceIdCookie){
      var newDeviceId = uuidv4();
      setCookie("self_device_id", newDeviceId, 3650);
    }
  })();

</script>

---

2. Create a variable to get your device id cookie

3. Create the trigger back to step1's tag

4. Done

Now you have the cookie of your own device-id if the user don't have one. You can use the cookie {{cookie_self_device_id}} in the GA4 configuration as a user property.