Version 4.52+ notes

For all release notes, see Tealium for Javascript release notes.

Overview

Version 4.52 introduces a queuing system for early tracking events in Single Page Applications (SPAs), a nonblocking_tags setting to improve Interaction to Next Paint (INP) scores, enhanced session counting for first-party setups, and performance optimizations.

Important notes for version 4.52+

Please review the following before implementing changes in version 4.52+:

• Queue for early tracking events: Only use the queue snippet with version 4.52 and later. Adding it with earlier versions will prevent utag.js from running.
• Session counting for first-party, reverse proxy and self-hosted setups: First-party and reverse-proxy customers should remove any previous custom session counting logic to avoid duplicate sessions. For self-hosted setups, contact Tealium support to deactivate your billing requests.

Queue for early tracking events

This version adds a queuing system for Tealium iQ’s tracking functions (utag.view, utag.link, utag.track), making them available immediately on page load. Previously, these functions would not work until utag.js fully loaded, causing errors or lost events in SPAs when called too early.

To enable this, add the following snippet above your existing Tealium iQ code:

(function(w){
  if(w.utag) return; var u=w.utag={}; u.e=[]; u.view=function(a,b,c){u.e.push({a:a,b:b,c:c,d:"view"})};
  u.link=function(a,b,c){u.e.push({a:a,b:b,c:c,d:"link"})};
  u.track=function(d,a,b,c){typeof d==="object" ? u.e.push({a:d.data,b:(d.cfg?d.cfg.cb:null),c:(d.cfg?d.cfg.uids:undefined),d:d.event}): u.e.push({a:a,b:b,c:c,d:d});
  };
})(window);

Adding this snippet ensures early tracking events are queued and processed as soon as utag.js executes. The queued events are processed in the order received.

Only use this snippet with version 4.52 and later. Adding it with earlier versions will prevent utag.js from running.

Nonblocking tags option

The new nonblocking_tags setting provides a way to make tags nonblocking, helping improve the INP score by allowing tags to load asynchronously. By default, tags are blocking, which ensures tracking but may delay page load times for heavy or resource-intensive tags. Enabling nonblocking_tags optimizes performance for users prioritizing INP scores for SEO.

Best Practice: Use nonblocking_tags for pages with resource-intensive tags that don’t need to block DOM rendering. Consider navigation delays on critical navigation and exit events, since nonblocking tags load without holding the page for tracking (which is why they improve the INP score).

For more information, see Settings: nonblocking_tags

Session counting for first-party setups

Adds session counting for first-party and reverse-proxy customers who previously needed custom configurations to measure sessions. The new setup standardizes session counting without requiring custom scripts, improving accuracy for first-party environments.

• First-party and reverse-proxy customers should remove any previous custom session counting logic to avoid duplicate sessions.
• For self-hosted setups, please contact Tealium support to deactivate your billing requests.

Performance enhancements

This release includes the following performance enhancements:

• Updates to minimize unnecessary cookie reads, improving performance on pages with multiple or complex cookies. The utag_main cookie now avoids repetitive reads without affecting cookie-based tracking or data storage. This enhancement is applied automatically with version 4.52.
• Addresses long-standing inconsistent behaviors that could create unexpected tracking issues. These fixes make Tealium iQ more predictable, particularly for advanced implementations:
  • Before Load Rules scoped Javascript extension: All extensions scoped to Before Load Rules now execute once per page load, even for tags called by UID. To retain the legacy behavior, set suppress_before_load_rules_with_uids to true. For more information, see Settings: suppress_before_load_rules_with_uids.
  • Event attribute overwrites: All tealium_* event attributes are now automatically overwritten by Tealium-generated values, except for tealium_visitor_id and tealium_event. This prevents conflicts from manually set tealium_* attributes in the data layer.