How to Handle Async Errors in Node.js?

1. Definition

Async errors occur during asynchronous operations like file handling, API calls, or database queries. These errors must be handled properly to prevent application crashes.

2. Using Callbacks (Error-first pattern)

const fs = require("fs");

fs.readFile("file.txt", (err, data) => {
  if (err) {
    console.error("Error:", err.message);
    return;
  }
  console.log(data.toString());
});

3. Using Promises (.catch)

const fs = require("fs").promises;

fs.readFile("file.txt", "utf8")
  .then(data => console.log(data))
  .catch(err => console.error("Error:", err.message));

4. Using Async/Await (try...catch)

const fs = require("fs").promises;

async function readFile() {
  try {
    const data = await fs.readFile("file.txt", "utf8");
    console.log(data);
  } catch (err) {
    console.error("Error:", err.message);
  }
}

readFile();

5. Best Practices

Always handle errors in async code
Use try...catch with async/await
Use .catch() for promises
Avoid unhandled promise rejections

6. Advantages

Prevents application crashes
Improves reliability
Better debugging
Cleaner and maintainable code