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Node.js Q&A

1 min read

Event Loop

An Event Loop is a loop that waits for events and then triggers a callback function when one of those events is detected. It is a mechanism that allows Node.js to perform non-blocking I/O operations, even though JavaScript is single-threaded.

Example:

setTimeout(() => console.log('Done'), 1000);
console.log('Hello');

In the above example, the setTimeout function is called with a delay of 1000 milliseconds. The console.log('Hello') statement is executed first, and then the setTimeout function is executed. After 1000 milliseconds, the callback function is executed and the message ‘Done’ is logged to the console.

Non-blocking Code

Non-blocking code is code that doesn’t block the execution of the program during its execution. In Node.js, non-blocking code is used to perform I/O operations asynchronously. This allows the program to continue executing other code while waiting for the I/O operation to complete.

In opposite to popular belief, async/await and promises are effectively blocking the execution of the rest of the function until the awaited promise resolves, therefore they are NOT non-blocking.

Non-blocking code examples:

  1. Child Processes (more)
  2. Worker Threads (more)
  3. Cluster Module (more)
  4. Non-blocking Native Modules (fs, http, etc.)
  5. Queues
  6. Streaming APIs

More is coming soon

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