Bits of .NET

📊 Arrays Are Everywhere

Lists of data need manipulation. Array methods filter, map, reduce, sort. Essential for data processing.

📝 Common Array Methods

// forEach: Iterate
const numbers = [1, 2, 3, 4, 5];
numbers.forEach(n => console.log(n));

// map: Transform each element
const doubled = numbers.map(n => n * 2);  // [2, 4, 6, 8, 10]

// filter: Keep matching elements
const evens = numbers.filter(n => n % 2 === 0);  // [2, 4]

// reduce: Accumulate
const sum = numbers.reduce((acc, n) => acc + n, 0);  // 15

// find: First match
const firstEven = numbers.find(n => n % 2 === 0);  // 2

// findIndex: Index of first match
const evenIndex = numbers.findIndex(n => n % 2 === 0);  // 1

// some: Any match
const hasEven = numbers.some(n => n % 2 === 0);  // true

// every: All match
const allEven = numbers.every(n => n % 2 === 0);  // false

// sort: Sort (with comparator)
const sorted = numbers.sort((a, b) => a - b);  // Ascending

// includes: Check existence
const hasThree = numbers.includes(3);  // true

🎯 Real-World Examples

// Filter active users
const activeUsers = users.filter(u => u.isActive);

// Get user names
const userNames = users.map(u => u.name);

// Sort by age
const sortedByAge = users.sort((a, b) => a.age - b.age);

// Calculate average age
const avgAge = users.reduce((sum, u) => sum + u.age, 0) / users.length;

// Group by category
const grouped = users.reduce((acc, user) => {
  if (!acc[user.role]) acc[user.role] = [];
  acc[user.role].push(user);
  return acc;
}, {});

// Find admin users
const admin = users.find(u => u.role === 'admin');

// Check if any admin
const hasAdmin = users.some(u => u.role === 'admin');

// Get unique values
const unique = [...new Set(numbers)];

💡 Chaining Methods

• Chain methods for cleaner code
• filter → map → sort → reduce
• Avoid multiple loops (performance)
• Use breakpoints to debug chains