ASYNC API
- Using non-blocking asynchronous APIs is even more important on Node than in the browser because Node is a single-threaded event-driven execution environment.
- "Single threaded" means that all requests to the server are run on the same thread (rather than being spawned off into separate processes).
SYNC ACTION
console.log('First');
console.log('Second');
ASYNC ACTION
setTimeout(function() {
console.log('First');
}, 3000);
console.log('Second');
REF
https://developer.mozilla.org/en-US/docs/Learn/Server-side/Express_Nodejs/Introduction