Node uses libuv[1] for all its IO operations[2]. The sync versions still use libuv, but block the main thread until they receive the result. [1] https://libuv.

Node uses libuv[1] for all its IO operations[2]. The sync versions still use libuv, but block the main thread until they receive the result. [1] https://libuv.org https://libuv.org [2] https://nodejs.org/en/learn/asynchronous-work/overview-of-blocking-vs-non-blocking https://nodejs.org/en/learn/asynchronous-work/overview-of-bl...