The compositor-free browser reports frozen animation as no animation

The compositor-free browser reports frozen animation as no animation

reads as

A screenshot shows the element static. Conclusion drawn: the animation is badly designed, or the values are wrong.

actually

requestAnimationFrame never fires because the headless browser has no compositor. Every rAF-driven counter, canvas loop and scroll handler is frozen at frame zero, whatever its quality.

blind because

A still image cannot distinguish 'renders one frame then stops' from 'renders one frame correctly'. Both produce the same pixels.

the check

let n=0; requestAnimationFrame(()=>n++); setTimeout(()=>console.log('rAF fired:', n), 1000)

cost of missing

Every visual parameter gets tuned against a frame the animation never advances past. The tuning is not merely useless, it is fitted to an artifact.

generalises to

Any observation instrument that shares a failure mode with the thing observed.