Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The renderStart read-only property of the PerformanceLongAnimationFrameTiming interface returns a DOMHighResTimeStamp indicating the start time of the rendering cycle, which includes Window.requestAnimationFrame() callbacks, style and layout calculation, ResizeObserver callbacks, and IntersectionObserver callbacks.
See Long animation frame timing for examples related to the Long Animation Frames API.