What is the JavaScript event loop?

It's the coordinator that processes tasks (macrotasks like setTimeout), microtasks (Promises), and rendering in strict order, keeping single-threaded JS non-blocking.

How does setTimeout(0) work in JavaScript?

It queues a macrotask for the next event loop turn, after current JS, microtasks, and rendering—not immediately.

Why do Promises run before setTimeout?

Promises queue microtasks, flushed before the next macrotask like timeouts.

🤖 AI & Machine Learning

JavaScript Event Loop Unraveled: A Experimental Series That Actually Sticks

JavaScript's async maze has tripped up devs for years. This series cuts through with experiments that build an unbreakable mental model.

theAIcatchup Apr 10, 2026 3 min read

Visual diagram of JavaScript event loop phases: macrotasks, microtasks, rendering

⚡ Key Takeaways

Build event loop mental model through experiments, not diagrams. 𝕏
Microtasks (Promises) always precede macrotasks (setTimeout). 𝕏
Rendering happens after microtasks and rAF, preventing UI blocks. 𝕏

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theAIcatchup

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#Async Await #JavaScript Event Loop #macrotasks #microtasks

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Originally reported by Dev.to

⚡ Key Takeaways

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