Anti-flicker

Anti-flicker is a technique that hides content until it's ready to display correctly, so visitors don't briefly see something that's about to change. Without it, you get a flash of the “before” state right before the “after” state takes over.

It shows up in a few common places: A/B testing tools that swap in a variant after the original page has already loaded, JavaScript that modifies content or styles after the initial render, web fonts that load in a moment after a fallback font appears (sometimes called FOUT, flash of unstyled text), and animations that need their starting state set before anything becomes visible. In each case, anti-flicker briefly delays or hides the page until the real, final version is ready.