Error classes in TypeScript are custom error objects that you can create to provide more specific information about errors that occur in your code.

By extending the built-in Error class or creating your own error classes, you can define custom error types with additional properties and behaviors. This is particularly useful for creating meaningful error messages and for distinguishing between different types of errors in your applications.

Here's how you can create and use error classes in TypeScript:

Extending the Error Class:

You can extend the Error class to create custom error classes. Here's an example:

javascriptclass MyCustomError extends Error {
  constructor(message: string) {
    super(message);
    this.name = 'MyCustomError';
  }
}

// Usage
try {
  // Some code that may throw an error
  throw new MyCustomError('This is a custom error message.');
} catch (error) {
  if (error instanceof MyCustomError) {
    console.error('Caught a custom error:', error.message);
  } else {
    console.error('Caught an error of an unexpected type:', error.message);
  }
}

In this example, we create a custom error class called MyCustomError by extending the built-in Error class. We provide a constructor to set the error message and specify the error's name. The custom error is then thrown and caught, allowing you to handle it separately from other error types.

Creating Your Own Custom Error Classes:

You can also create your own error classes without extending the Error class:

javascriptclass DatabaseError {
  constructor(public code: number, public message: string) {}
}

// Usage
try {
  // Some database operation that may throw an error
  throw new DatabaseError(404, 'Record not found.');
} catch (error) {
  if (error instanceof DatabaseError) {
    console.error('Database Error (Code:', error.code, '):', error.message);
  } else {
    console.error('Caught an unexpected error:', error);
  }
}

In this example, we create a custom error class DatabaseError with specific properties for the error code and message. You can use this class to throw and catch database-related errors.

Custom error classes provide several benefits:

• They help make your code more readable by distinguishing different types of errors.

• They allow you to include additional properties or metadata in the error object.

• They make error handling more robust and specific.

• They enable easier debugging and troubleshooting by providing detailed error information.

Custom error classes are a powerful way to improve error handling in your TypeScript code by allowing you to create well-defined error types tailored to your application's needs.