module-4.3-error-handling-techniques.md

4.3. Error Handling Techniques

Error handling is a fundamental part of writing robust and reliable web applications. This section covers various techniques for handling errors effectively.

Try...Catch Blocks

One of the most common error handling techniques in JavaScript is using try...catch blocks to catch and gracefully handle exceptions.

Example:

try {
  // Code that may throw an error
  const result = someFunction();
} catch (error) {
  // Handle the error
  console.error('An error occurred:', error.message);
}

In this example, the try block contains code that may throw an error. If an error occurs, the catch block handles it by logging an error message.

Throwing Custom Errors

You can throw custom errors to provide more informative error messages and categorize errors based on your application's needs.

Example:

function divide(a, b) {
  if (b === 0) {
    throw new Error('Division by zero is not allowed.');
  }
  return a / b;
}

try {
  const result = divide(10, 0);
  console.log('Result:', result);
} catch (error) {
  console.error('An error occurred:', error.message);
}

In this example, the divide function throws a custom error with a specific message when division by zero is attempted.

Error Objects

JavaScript provides built-in error objects such as Error, TypeError, and ReferenceError. You can use these to capture and identify specific types of errors.

Example:

try {
  // Attempt to access an undefined variable
  const value = someUndefinedVariable;
} catch (error) {
  if (error instanceof ReferenceError) {
    console.error('ReferenceError occurred:', error.message);
  } else {
    console.error('An error occurred:', error.message);
  }
}

In this example, we catch a ReferenceError and log an error message specific to this error type.

Benefits

• Error handling techniques allow you to gracefully handle exceptions and prevent your application from crashing.
• Custom errors and error objects enable you to provide informative error messages and categorize errors for easier debugging.

Understanding error handling techniques is essential for building web applications that can recover from unexpected situations and provide users with meaningful error messages.