Anti-Flicker Script
An anti-flicker script is a piece of JavaScript used by many Client-Side A/B Testing tools. Its purpose is to prevent the Flicker Effect, where a user briefly sees the original page before the test version loads and replaces it. The script works by hiding the entire page content until the test variation is ready to be displayed. While this solves the flicker, it introduces a significant performance penalty by forcing the user to look at a blank screen, which negatively impacts crucial metrics like Largest Contentful Paint (LCP).
Related web performance terms
- A/B Testing
A/B testing is a method of comparing two versions of a webpage to see which one performs better. For example, an e-commerce store might show 50% of its visitors a green "Buy Now" button (Version A)…
- AVIF
AVIF (AV1 Image File Format) is a modern, next-generation image format that provides significantly better compression than older formats like JPEG and WebP.
- Abandonment Rate
Abandonment Rate is a metric that measures the percentage of users who start a specific process (like a checkout funnel or a sign-up form) but leave before completing it.
- Above the Fold
This is a term originally from newspaper design that now refers to the portion of a webpage that is visible to a user without having to scroll down. Content "above the fold" is the very first thing a user sees.