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Learning Objectives & Key Takeaways
0 / 4 Completed- Understand JavaScript core architecture and runtime execution model
- Audit real-world latency, throughput benchmarks, and memory footprint
- Implement zero-downtime deployment patterns with resilience guards
- Verify code snippets and architect blueprints against production SLOs
Practise it next
JavaScript interview questions, quiz and handbook in your Learning Dashboard
What you will learn
- Synchronous code runs first, then all microtasks, then one task.
- Promise callbacks and queueMicrotask are microtasks; timers are tasks.
- Long microtask chains can starve rendering.
One thread, many queues
JavaScript runs your code on a single thread. Asynchronous APIs do not run code in parallel; they schedule callbacks into queues, and the event loop decides what runs next.
Interviewers love event-loop puzzles because the answer reveals whether you understand those queues or only memorised examples.
In the rest of this story
- The order of operations
- Predict the output
- Practical consequences
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