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← All coursesThe JavaScript Event Loop: Predicting Execution Order6 levels · 28 lessons

Nothing interrupts a running stack~7 min
Treat timer delays as minimums~5 min
A promise callback runs before a timer queued earlier~6 min
An async function runs synchronously until its first await~6 min
How the Event Loop Runs · Review~5 min

Count the hops in a promise chain~6 min
Predict which resolution pays extra hops~6 min
Predict what deferred callbacks see~6 min
Get the concurrency you wrote~6 min
Promises and Deferred Callbacks · Review~5 min

See why a test click and a real click log different orders~7 min
Trace Which Code Catches an Async Throw~6 min
Step a Paused Stack Frame by Hand~7 min
The Microtask Checkpoint in Detail · Review~5 min

Starve the frame on purpose~7 min
Put your code before the paint~7 min
See the ticks inside for await~6 min
The Event Loop and Rendering · Review~5 min

Place a callback in the phase that fires it~7 min
Know when you can't predict the order~6 min
Spot the line that stalls every request~6 min
Trace where a rejection escapes the process~6 min
Node.js Event Loop Phases · Review~5 min

Carry request identity through awaits~7 min
Decide which workload leaves the main thread~6 min
Cancel work you already started~6 min
Consume a stream and exit it safely~6 min
Context, Workers, Cancellation and Streams · Review~5 min

Course

The JavaScript Event Loop: Predicting Execution Order

Say which line of async JavaScript runs first, in the browser and in Node, without running the code.

Start free: Nothing interrupts a running stack

The levels

Level I · 5 lessonsHow the Event Loop Runs