Question 1

What is the JavaScript event loop?

Accepted Answer

The JavaScript event loop is the runtime mechanism that orchestrates execution between the call stack, Web APIs, microtask queue, and macrotask queue. It runs synchronous code, drains microtasks (Promise.then, queueMicrotask), then picks up one macrotask at a time. JS Visualizer animates this entire dance so you can see exactly what runs when.

Question 2

How does JS Visualizer help me learn async/await?

Accepted Answer

JS Visualizer steps through async functions and shows you when execution suspends, when the resulting Promise resolves, when the resume callback enters the microtask queue, and when the await expression continues. You see the difference between Promise.then chaining, queueMicrotask, and setTimeout in real time.

Question 3

What is the difference between microtasks and macrotasks in JavaScript?

Accepted Answer

Microtasks (Promise.then callbacks, queueMicrotask) run immediately after the current synchronous task finishes — the engine drains the entire microtask queue before any macrotask. Macrotasks (setTimeout, setInterval, I/O events) run one per event-loop tick. JS Visualizer separates the two queues visually so the ordering is unmistakable.

Question 4

Is JS Visualizer free to use?

Accepted Answer

Yes — JS Visualizer is completely free, runs entirely in your browser, and requires no signup. There is no paid tier.

Question 5

Do I need to install anything?

Accepted Answer

No. JS Visualizer runs entirely in your browser — no installation, account, or backend required. Just open the page and start stepping through code.

Question 6

Can I visualize my own JavaScript code?

Accepted Answer

Yes. Paste any JavaScript snippet into the Monaco editor and click RUN. The visualizer steps through it, animating the call stack, queues, and memory graph as your code executes.