| 1 | What is 'event loop lag' (or 'event loop delay'), and how would you monitor it in a production Node.js application? Node.js › Event Loop & Non-blocking IO | Node.js | Event Loop & Non-blocking IO | Advanced |
| 2 | What is the poll phase of the event loop, and under what specific conditions does it block waiting versus move on immediately? Node.js › Event Loop & Non-blocking IO | Node.js | Event Loop & Non-blocking IO | Advanced |
| 3 | What is the event loop, and why does it allow Node.js to handle many concurrent operations despite being single-threaded? Node.js › Event Loop & Non-blocking IO | Node.js | Event Loop & Non-blocking IO | Beginner |
| 4 | How does the V8 JavaScript engine's microtask queue interact with the Node.js event loop's macrotask phases, and why does this occasionally surprise developers? Node.js › Event Loop & Non-blocking IO | Node.js | Event Loop & Non-blocking IO | Advanced |
| 5 | What does 'non-blocking I/O' mean, and how does a Node.js function like fs.readFile() achieve it compared to fs.readFileSync()? Node.js › Event Loop & Non-blocking IO | Node.js | Event Loop & Non-blocking IO | Intermediate |
| 6 | How does the event loop handle a large synchronous loop (like processing a huge array with a for loop), and what problem does this cause? Node.js › Event Loop & Non-blocking IO | Node.js | Event Loop & Non-blocking IO | Intermediate |
| 7 | How would you measure how 'busy' the event loop is in a running Node.js process using a simple technique? Node.js › Event Loop & Non-blocking IO | Node.js | Event Loop & Non-blocking IO | Intermediate |
| 8 | What is the difference between concurrency and parallelism, and which one does Node.js's event loop actually provide by default? Node.js › Event Loop & Non-blocking IO | Node.js | Event Loop & Non-blocking IO | Beginner |
| 9 | What is a callback queue (or task queue) in the context of the Node.js event loop, and how does it relate to the call stack? Node.js › Event Loop & Non-blocking IO | Node.js | Event Loop & Non-blocking IO | Beginner |
| 10 | What are the distinct phases of the Node.js event loop, and what kind of callbacks does each phase execute? Node.js › Event Loop & Non-blocking IO | Node.js | Event Loop & Non-blocking IO | Advanced |