Bits of .NET

📊 Native GroupBy Finally Arrived

_.groupBy() required Lodash. Object.groupBy() is now native. Group arrays by any criteria. No more manual reduce hacks.

📝 Basic Usage

const users = [
  { name: 'Alice', role: 'admin' },
  { name: 'Bob', role: 'user' },
  { name: 'Charlie', role: 'admin' },
  { name: 'Diana', role: 'user' }
];

// Group by role
const grouped = Object.groupBy(users, user => user.role);

// Result:
// {
//   admin: [{ name: 'Alice', role: 'admin' }, { name: 'Charlie', role: 'admin' }],
//   user: [{ name: 'Bob', role: 'user' }, { name: 'Diana', role: 'user' }]
// }

console.log(grouped.admin.length); // 2

🎯 Real-World Examples

// Group by date (orders)
const orders = [
  { id: 1, date: '2024-01-15', total: 100 },
  { id: 2, date: '2024-01-15', total: 200 },
  { id: 3, date: '2024-01-16', total: 150 }
];

const byDate = Object.groupBy(orders, order => order.date);
// {
//   '2024-01-15': [order1, order2],
//   '2024-01-16': [order3]
// }

// Group by first letter
const words = ['apple', 'banana', 'apricot', 'blueberry', 'avocado'];
const byFirstLetter = Object.groupBy(words, word => word[0]);
// {
//   a: ['apple', 'apricot', 'avocado'],
//   b: ['banana', 'blueberry']
// }

// Group by even/odd
const numbers = [1, 2, 3, 4, 5, 6];
const byParity = Object.groupBy(numbers, n => n % 2 === 0 ? 'even' : 'odd');

// Group by age bracket
const people = [
  { name: 'Alice', age: 25 },
  { name: 'Bob', age: 32 },
  { name: 'Charlie', age: 28 },
  { name: 'Diana', age: 45 }
];

const byAgeGroup = Object.groupBy(people, p => {
  if (p.age < 30) return '20s';
  if (p.age < 40) return '30s';
  return '40+';
});

✅ Map.groupBy for Maps

// Map.groupBy returns Map instead of Object
const usersMap = Map.groupBy(users, user => user.role);
// Map {
//   'admin' => [user1, user3],
//   'user' => [user2, user4]
// }

usersMap.get('admin'); // Array of admin users

💡 Browser Support

• Chrome 117+ ✅
• Firefox 119+ ✅
• Safari 17.4+ ✅
• Edge 117+ ✅
• Fallback: Use reduce() for older browsers