JavaScript · Senior · Question 59 of 75

Why can this code freeze the page even though it uses promises?

function loop() { Promise.resolve().then(loop); }
loop();

✓Correct answer: Each microtask schedules another, so the microtask queue never empties and rendering never happens
2Promises run on a separate thread and overload the CPU
3It doesn't freeze; promises yield to rendering

Explanation

The browser renders only between macrotasks after the microtask queue drains. Use setTimeout, MessageChannel or scheduler.yield() to give rendering a chance.

Why can this code freeze the page even though it uses promises?

Explanation

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