Error handling and debugging techniques in JavaScript

// Basic try-catch
try {
  const result = riskyOperation();
  console.log('Success:', result);
} catch (error) {
  console.error('Error occurred:', error.message);
}

// Try-catch-finally
try {
  performOperation();
} catch (error) {
  console.error('Error:', error);
} finally {
  cleanup(); // Always runs
}

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

try {
  console.log(divide(10, 0));
} catch (error) {
  console.error(error.message);
}

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

function validateUser(user) {
  if (!user.email) {
    throw new ValidationError('Email is required');
  }
}

try {
  validateUser({ name: 'Alice' });
} catch (error) {
  if (error instanceof ValidationError) {
    console.error('Validation failed:', error.message);
  }
}

// Console methods
console.log('Regular log');
console.info('Information');
console.warn('Warning!');
console.error('Error!');

const users = [
  { id: 1, name: 'Alice', age: 25 },
  { id: 2, name: 'Bob', age: 30 }
];
console.table(users);

// Console timing
console.time('operation');
for (let i = 0; i < 1000000; i++) {}
console.timeEnd('operation');

// Console trace
function level1() { level2(); }
function level2() { level3(); }
function level3() { console.trace('Call stack'); }
level1();

// Debugger statement
function complexFunction(data) {
  debugger; // Pauses in DevTools
  return processData(data);
}

// Global error handler
window.addEventListener('error', (event) => {
  console.error('Global error:', event.error);
  console.error('File:', event.filename);
  console.error('Line:', event.lineno);
});

// Unhandled promise rejections
window.addEventListener('unhandledrejection', (event) => {
  console.error('Unhandled rejection:', event.reason);
});

// Defensive programming
function safeAccess(obj, path, defaultValue = null) {
  return path.split('.').reduce((current, key) => {
    return current?.[key];
  }, obj) ?? defaultValue;
}

const user = { profile: { name: 'Alice' } };
console.log(safeAccess(user, 'profile.name')); // 'Alice'
console.log(safeAccess(user, 'profile.age', 0)); // 0