The Main Thread Is a Queueing Problem
A practical model for understanding why browser work feels instant until one task holds the main thread for too long.
Series
Understanding JavaScript
3 parts, ordered so each article can assume what the previous one established.
- 01
- 02
What "Non-Blocking JavaScript" Actually Means
JavaScript can start asynchronous work without making the single main thread magically perform two tasks at once.
- 03
Tasks, Microtasks, and the Rendering Gap
A small ordering rule explains why a resolved promise can still postpone painting and user input.