Flicker is the occurrence of default content being momentarily displayed to the visitor before it is replaced with the content you intended to show the visitor, making it seem to the visitor that the content flickered. Visitors can sometimes interpret flicker as a problem with the site, potentially causing the visitor to lose confidence in the site or brand. Flicker can also cause visitor dissatisfaction if, for example, they see a discount they like "flicker away" to be replaced with a lesser discount. Flicker is a symptom of encountering a delay in loading the content displayed, also called "tests", asynchronously.
You can load Test & Target, a popular solution for A/B and Multivariate testing, either synchronously or asynchronously. Both methods provide benefits and issues, and it is important to understand each in order to make an informed decision.
If you choose to load your tests synchronously, you will not see flicker occur. However, loading content synchronously means that the entire page must wait to receive that content before it parses and displays the rest of the page. If the content the page is trying to load is unavailable, the page will "hang", meaning it will appear to stop loading. If the delay is too long, the page becomes unavailable to visitors completely, resulting in lost traffic, conversions, etc.
Asynchronous loading circumvents the issue of unavailable content halting page load because the browser continues to load the rest of the page while it waits for the pending content. However, if there is a long enough delay between the browser encountering the offer on the page and retrieving the offer's content, visitors may briefly see the default content. This is the flicker phenomenon.
Going forward, utag.footer.js is officially deprecated and no longer an option. Older implementations that are using utag.footer.js will continue to function as before. You will not have to change the scope for your old Content Modification Extensions. The old Content Modifications Extensions originally scoped to 'Footer' will appear to be scoped to 'DOM Ready', but they will still publish to the utag.footer.js file.
The utag.sync.js file replaces the functionality of the old utag.footer.js file. When you use the utag.sync.js, make sure you include its file reference within the head tags at the top of the page's code. You must include utag.sync.js on your page if you want to use Flicker Free Test & Target.
Note: If a load rule does not allow the Test & Target Tag to load, then the utag.js file will show the hidden nodes and display the default content instead.
We've updated the Test & Target Extension to handle our Flicker Free solution. Before you begin using the Flicker Free TnT Extension:
Include utag.sync.js within the head tag of your page's code. You cannot use the Flicker Free functionality without this.
First, you need to enable the appropriate Publish Setting:
You must delete the old Tag Template for Test & Target.
Setting up the Extension to use Flicker free is as simple as checking the 'Flicker Free' box in the Extension settings. Be aware that if you use Flicker Free, you must select 'Replace Node Content (leave default)' for the Mod Position selection. All other configurations remain as they were before, as described in the Test & Target article.