If it is done in JS it is going to be done on the CPU. Probably on the main thread even which could make it choppy. If it is done with CSS it is much more like

If it is done in JS it is going to be done on the CPU. Probably on the main thread even which could make it choppy. If it is done with CSS it is much more likely it'll be done by the GPU and will not interrupt the main thread and cause 'jank'.