What are the differences between callbacks, promises, and async/await in Node.js?

What are the differences between callbacks, promises, and async/await in Node.js?

Callbacks are functions passed as arguments to other functions, executed after a task completes. Promises represent a value that may be available now or in the future, allowing for cleaner asynchronous code. Async/await is syntactic sugar over promises, making asynchronous code look synchronous.

Can you give me an example of each method?

Sure! For callbacks:

fs.readFile('file.txt', (err, data) => {
  if (err) throw err;
  console.log(data);
});

For promises:

fs.promises.readFile('file.txt')
  .then(data => console.log(data))
  .catch(err => console.error(err));

And for async/await:

async function readFile() {
  try {
    const data = await fs.promises.readFile('file.txt');
    console.log(data);
  } catch (err) {
    console.error(err);
  }
}
readFile();

Which method is preferred for new projects?

Async/await is generally preferred for new projects due to its readability and ease of use, especially for complex asynchronous flows.

Are there any performance differences between them?

In terms of performance, there isn't a significant difference for most use cases. However, callbacks can lead to 'callback hell' which can affect maintainability, while promises and async/await provide better structure.