Non-blocking I/O operations allow a single process to serve multiple requests at the same time. Instead of the process being blocked and waiting for I/O operations to complete, the I/O operations are delegated to the system, so that the process can execute the next piece of code.

What is non-blocking method?

Non-blocking means that if an answer can't be returned rapidly, the API returns immediately with an error and does nothing else. So there must be some related way to query whether the API is ready to be called (that is, to simulate a wait in an efficient way, to avoid manual polling in a tight loop).

How does node prevents blocking code?

Node is assumed to prevent blocking code by using a single-threaded event loop. ... While non-blocking operations allow further pieces of code to execute without making them wait and use callbacks when they are completed. Thus, blocking code can be said to work synchronously while non-blocking code works asynchronously.