How can you create custom error objects?

TL;DR

To create custom error objects in JavaScript, you can extend the built-in Error class. This allows you to add custom properties and methods to your error objects. Here's a quick example:

class CustomError extends Error {
  constructor(message) {
    super(message);
    this.name = 'CustomError';
  }
}

try {
  throw new CustomError('This is a custom error message');
} catch (error) {
  console.log(error.name); // CustomError
  console.log(error.message); // This is a custom error message
}

Extending the `Error` class

To create a custom error object, you can extend the built-in Error class. This allows you to inherit the properties and methods of the Error class while adding your own custom properties and methods.

class CustomError extends Error {
  constructor(message) {
    super(message);
    this.name = 'CustomError';
  }
}

Adding custom properties

You can add custom properties to your custom error class to provide more context about the error.

class CustomError extends Error {
  constructor(message, errorCode) {
    super(message);
    this.name = 'CustomError';
    this.errorCode = errorCode;
  }
}

try {
  throw new CustomError('This is a custom error message', 404);
} catch (error) {
  console.log(error.name); // CustomError
  console.log(error.message); // This is a custom error message
  console.log(error.errorCode); // 404
}

Custom methods

You can also add custom methods to your custom error class to handle specific error-related logic.

class CustomError extends Error {
  constructor(message, errorCode) {
    super(message);
    this.name = 'CustomError';
    this.errorCode = errorCode;
  }

  logError() {
    console.error(`${this.name} [${this.errorCode}]: ${this.message}`);
  }
}

try {
  throw new CustomError('This is a custom error message', 404);
} catch (error) {
  error.logError(); // CustomError [404]: This is a custom error message
}

Using `instanceof` to check for custom errors

You can use the instanceof operator to check if an error is an instance of your custom error class.

try {
  throw new CustomError('This is a custom error message', 404);
} catch (error) {
  if (error instanceof CustomError) {
    console.log('Caught a CustomError');
  } else {
    console.log('Caught a different type of error');
  }
}

How can you create custom error objects?

TL;DR