🎯 Learning Objectives

By the end of this lesson, you will be able to:

  • Implement comprehensive error handling strategies
  • Create custom error classes
  • Use error boundaries in applications
  • Handle errors in async operations
  • Build robust error reporting systems

📚 Error Handling Strategies

Custom Error Classes

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

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

// Usage
function validateUser(user) {
    if (!user.email) {
        throw new ValidationError('Email is required', 'email');
    }
    if (!user.password) {
        throw new ValidationError('Password is required', 'password');
    }
}

Error Boundary Pattern

class ErrorBoundary {
    constructor() {
        this.errors = [];
    }

    async execute(fn) {
        try {
            return await fn();
        } catch (error) {
            this.errors.push({
                error,
                timestamp: new Date(),
                context: 'execution'
            });
            throw error;
        }
    }

    getErrors() {
        return this.errors;
    }

    clearErrors() {
        this.errors = [];
    }
}

🎯 Key Takeaways

  1. Custom errors provide specific error types
  2. Error boundaries catch and handle errors
  3. Error reporting helps with debugging
  4. Graceful degradation improves user experience

Next Lesson: Lesson 10: Mini Project - GitHub Profile Finder