Error Handling

Intermediate~18 min

TypeScript error handling uses custom error classes and type guards for robust, type-safe error management.

Error Handling

// Error Handling in TypeScript

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

class NetworkError extends Error {
    statusCode: number;
    
    constructor(message: string, statusCode: number) {
        super(message);
        this.name = "NetworkError";
        this.statusCode = statusCode;
    }
}

function validateEmail(email: string): void {
    if (!email.includes("@")) {
        throw new ValidationError("Invalid email format");
    }
}

async function fetchData(url: string): Promise<any> {
    try {
        const response = await fetch(url);
        if (!response.ok) {
            throw new NetworkError("Request failed", response.status);
        }
        return await response.json();
    } catch (error) {
        if (error instanceof NetworkError) {
            console.error(`Network error (${error.statusCode}):`, error.message);
        } else if (error instanceof ValidationError) {
            console.error("Validation error:", error.message);
        } else {
            console.error("Unknown error:", error);
        }
        throw error;
    }
}

console.log("Error handling demonstrated");

Output

Click Run to execute your code

Custom Errors: Extend Error class for specific error types

Best Practice: Create custom error classes for different error types. Use instanceof to check error types.

Summary

Extend Error for custom errors
Use instanceof for type checking
Always handle errors in async code
Type-safe error handling

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Error Handling

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