Node.js native methods have Sync attached methods like fs.writeFileSync, crypto.hkdfSync, child_process.execSync. JavaScript in the browser is implemented asynchronously with all native functions that require thread blocking, but Sync methods in Node.js actually block threads until the task is complete.
When using Callback or Promise in Node.js, if only asynchronous logic is executed internally, it becomes possible to manage asynchronous tasks while proceeding with other tasks without stopping the main thread (using count for Callbak, Promise.all).
Sync method runs the next line after work, so it is easy to identify the order of execution and easy to code. However, the main thread is blocked, so you can't do more than one task at a time.
Think about the next example.
const syncFunc = () => {
for (let i = 0; i < 100; i++) fs.readFileSync(`/files/${i}.txt`);
console.log('sync done');
};
const promiseFunc = async () => {
await Promise.all(Array.from({length: 100}, (_,i) => fs.promises.readFile(`/files/${i}.txt`)));
console.log('promise done');
};
The promise function ends much faster when there is no problem reading all 100 txt files.
This Sync feature applies equally to libraries made of C language. If you look at the following code, you can see the difference in implementation in C++.
In conclusion, I think it's a matter of choice. There is no problem using Sync method if the code you make is logic that goes on a single thread that doesn't matter if the main thread is blocked(like simple macro). However, if you are making logic where performance issues such as servers are important and the main thread should not stop as much as possible for thread or asynchronous management, you can choose Promise or Callback.
