Asynchronous Vs synchronous in NodeJS

Question

I\'m new to NodeJS. I have seen there are separate asynchronous and synchronous functions for the same task (ex: {fs.writeFile,fs.writeFileSync} , {fs.read, f

Answer 1

Synchronous is a blocking call, where the thread is blocked until that call is over. Asynchronous is a non-blocking call, where the thread continues to execute the rest, why the call is executed separately.

Quoting from NodeJS Documentations:

Blocking is when the execution of additional JavaScript in the Node.js process must wait until a non-JavaScript operation completes. This happens because the event loop is unable to continue running JavaScript while a blocking operation is occurring.

Blocking methods execute synchronously and non-blocking methods execute asynchronously.

The use of Async methods Vs Sync methods:

If you call is an extensive operation like an I/O operation (Files, DB accesses etc), do use Async methods, because you don't want to block the entire process while and extensive operation is being carried out.

But if it is a regular call, where the result of it, is important for the rest of the process to function, do use Sync methods, where the process will halt until the call is completed.

If you are using AWS lambda for example, making an async call (will do the I/O operation asynchronously), might terminate the Lambda function as soon as the rest of the process is finished. So it is important identify when to use sync calls and async calls.

For more information, read the following doc.