JavaScript - Errors, try/catch, and Error Handling

Overview

Estimated time: 10–15 minutes

JavaScript provides structured error handling with try, catch, finally, and the Error object. Mastering these is essential for robust, user-friendly applications.

Learning Objectives

• Understand JavaScript's error types and the Error object
• Use try/catch/finally for error handling
• Throw and catch custom errors
• Best practices for error management

Prerequisites

• JavaScript - Currying & Higher-Order Functions

Explanation

JavaScript errors can be runtime (e.g., ReferenceError, TypeError) or custom (thrown by your code). Use try/catch to handle exceptions and prevent crashes.

Syntax

try {
  // code that may throw
} catch (err) {
  // handle error
} finally {
  // always runs
}

Throwing Custom Errors

function divide(a, b) {
  if (b === 0) throw new Error('Division by zero');
  return a / b;
}

try {
  divide(10, 0);
} catch (e) {
  console.error(e.message); // Division by zero
}

Common Pitfalls

• Not all errors can be caught (e.g., syntax errors, some async errors)
• Swallowing errors without logging or user feedback
• Using throw 'string' instead of throw new Error()

Summary

Use try/catch to handle errors gracefully. Always provide meaningful error messages and avoid hiding problems from users or developers.