How to Extend Errors in JavaScript with ES6 Classes?

Extending Errors in JavaScript with ES6 Classes

In JavaScript, handling errors often requires the use of instances of the Error type. However, developers may also want to add additional functionality or properties to these errors.

To extend the Error type, ES6 introduced the ability to subclass it. This allows you to create custom error types that inherit from the base Error type while adding your own specific enhancements.

Creating a Custom Error Class in ES6

Here's how you can create a custom error class called MyError that extends the Error class:

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

Within this class, you can define additional properties and methods specific to your custom error type. For instance, you could add a property to store a specific status code or a method to format the error message in a particular way.

Throwing Instances of Your Custom Error

Once you have defined your custom error class, you can throw instances of it:

throw new MyError('An error occurred.');

The thrown error instance will be instanceof Error and also have access to any additional properties or methods you defined in your custom class.

Conclusion

Subclassing the Error type in JavaScript using ES6 classes is an effective way to extend the functionality of errors while maintaining their core characteristics. This approach allows developers to create custom error types tailored to their specific needs, providing both flexibility and consistency in error handling.

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