Interactive, step-by-step explanations of JavaScript, React and Next.js.
Latest - JavaScript
Why does setTimeout(fn, 0) run after a Promise, and why does code after await come back later? Step through the call stack, the microtask queue and the macrotask queue one line at a time, and guess the output before you look.
November 8, 2026 - 6 min
May 2, 2025 - 13 min
August 4, 2024 - 8 min
April 7, 2024 - 21 min
February 4, 2024 - 6 min
February 3, 2024 - 13 min