The Node.js Event Loop Explained

Short summary

The Node.js event loop manages asynchronous operations by delegating I/O tasks to the system and executing their callbacks when the call stack empties, enabling a single thread to handle many concurrent requests. It continuously checks the call stack and task queue, moving callbacks only when ready. This design—avoiding blocked waiting—is why Node.js scales efficiently despite single-threaded execution.

• •Event loop enables Node.js to delegate async tasks (file reads, timers, APIs) outside the main thread
• •Call stack empties before the event loop moves callbacks from task queue to execution
• •Single-threaded Node.js scales without blocking because of this asynchronous architecture

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