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, or never. Async/await is syntactic sugar over promises, allowing for a more synchronous style of writing asynchronous code.

Can you give me an example of each?

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 one is better to use?

It depends on the context. Callbacks can lead to 'callback hell' if not managed well. Promises are cleaner and help avoid that, while async/await provides the most readable and maintainable code, especially for complex asynchronous operations.

Are there any performance differences?

In general, the performance differences are negligible for most applications. However, async/await can introduce slight overhead due to its syntactic sugar, but the benefits in code clarity often outweigh this.