requestAnimationFrame: The Missing Scheduling Layer

This is the sixth article in a series on how JavaScript actually runs. You can read the full series here or on my website . In the last article , we established that: The browser will not render while a macrotask is running nor while microtasks are draining. Instead, rendering only happens at stable boundaries. But this creates a new problem: If rendering only happens at specific boundaries, how do we run code just before a render? If we want smooth animation, frame-aligned updates, or visual st