What are some examples of custom error usage in programming?

What are some examples of custom error usage in programming?

Custom errors are user-defined error types that help in handling specific error scenarios. For example, in JavaScript, you can create a custom error class like this:

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

This allows you to throw and catch specific errors more effectively.

Can you give me a real-world scenario where custom errors are useful?

Sure! In a web application, if a user submits a form with invalid data, you can throw a ValidationError. This way, you can handle it specifically and provide user-friendly feedback, like highlighting the fields that need correction.

How do I catch custom errors in my code?

You can catch custom errors using a try-catch block. For example:

try {
    // code that may throw a ValidationError
} catch (error) {
    if (error instanceof ValidationError) {
        console.error('Validation error:', error.message);
    } else {
        console.error('An unexpected error occurred:', error);
    }
}

Are there any best practices for using custom errors?

Yes! Some best practices include:

1. Always extend the built-in Error class.
2. Include meaningful messages.
3. Use specific error types for different scenarios.
4. Document your custom errors for better maintainability.