How to Handle Errors for Async Code in Node js

Question

With the help of code, can you explain to me how to Handle Errors for Async Code in Node.js

Answer 1

To handle errors in the correct way when writing asynchronous code in Node.js, there are a few techniques used in different situations:

Error-First Callbacks: This is a common pattern in Node.js. In this pattern, the callback function receives an error as its first argument. When an error occurs, the callback is called with the error object; otherwise, it continues with the data. 

For example:

fs.readFile('/non-existent-file', (err, data) => {

  if (err) {

console.error('Error:', err);

  } else {

    console.log('Data:', data);

  }

});

Promises and .catch(): When working with Promises, you can handle errors by chaining a .catch() method. This catches any errors that occur in the Promise chain:

somePromiseFunction()

  .then(result => console.log(result))

  .catch(err => console.error('Error:', err));

Global Error Handling: It is possible to catch an uncaught exception or any unhandled promise rejection, using global event handlers like this in Node.js:

process.on('uncaughtException', (error) => {

  console.error('Uncaught Exception:', error);

});

process.on('unhandledRejection', (reason, promise) => {

  console.error('Unhandled Rejection at:', promise, 'reason:', reason);});