Hey r/learnjavascript! I always struggled to explain WHY this prints in this order: console.log('A'); setTimeout(() => console.log('B'), 0); Promise.resolve().then(() => console.log('C')); console.log('D'); // Output: A, D, C, B The textbook answer ("microtasks flush before tasks") never really clicked for me until I could SEE it happen. So I built JS Visualizer — a free browser tool that animates each step. You paste code, hit Run, and see: - Functions entering/leaving the call stack - setTimeout/fetch/Promises moving through Web APIs - The microtask queue flushing before the task queue - The event loop phase changing in real time You can set breakpoints (click the gutter), step one action at a time, control playback speed, and share code via URL. 20+ built-in examples covering Promise chaining, async/await, closure gotchas, timer ordering, etc.…