Error Handling Best Practices in Node.js

Node.js, an important runtime environment for server-side applications, has a set of best practices for handling errors. Two of these practices include using try/catch for synchronous code and using Promises or async/await for asynchronous error handling.

Using try/catch for Synchronous Code

In Node.js, errors that occur in synchronous code can be caught and handled using a try/catch block. This method is commonly used because it allows developers to detect and handle errors immediately and at the exact location of their occurrence. Here's a simple example:

try {
  // run some code here
} catch (error) {
  // handle errors here
}

In the above code, if an error occurs within the try block, the execution immediately transfers to the catch block where the error can be managed in isolation from the rest of the code.

Using Promises or async/await for Asynchronous Error Handling

Asynchronous errors in Node.js, on the other hand, are best handled using Promises or async/await. These features of the JavaScript language provide a convenient way to write asynchronous code in a synchronous manner.

Here is an example of error handling with Promises:

doSomethingAsync()
  .then(result => {
    // handle result here
  })
  .catch(error => {
    // handle error here
  });

Likewise, with async/await you can also write code that looks synchronous but is really asynchronous:

async function someFunction() {
  try {
    const result = await doSomethingAsync();
    // handle result here
  } catch (error) {
    // handle error here
  }
}

In both examples, if an error occurs during the execution of the doSomethingAsync function, it's passed to the catch block. This strategy allows programmers to concentrate error-handling code in one place.

Best Practices in Error Handling

While the process.on('error', callback) is used to catch uncaught exceptions in a Node.js application, using it as a global error handler is not considered a best practice. It might hide bugs and can make applications difficult to debug.

Also, exclusively handling errors at the root level of the application isn't advisable. Although it’s a good practice to have a global error handler for unhandled errors, it's not a substitute for local error handling. As noted above, catching errors locally using 'try/catch' or 'Promises/async/await' allows you to respond to and recover from errors in a much more fine-grained manner.

In conclusion, the best approach in Node.js error handling is to combine several methods. This approach involves handling errors locally where they occur and also having a safety net at the root level to catch anything that might slip through.