class CustomError extends Error {

  constructor(message) {

    super(message);

    this.name = 'CustomError';

  }

}

​

// Usage

try {

  throw new CustomError("This is a custom error!");

} catch (error) {

  if (error instanceof CustomError) {

    console.error("Caught a custom error:", error.message);

  } else {

    console.error("Caught an unknown error:", error.message);

  }

}