JavaScript Array Methods

// Loop through array
const arr = [1, 2, 3];
arr.forEach((item, index) => {
    console.log(item, index);
});

// Transform array
const nums = [1, 2, 3];
const doubled = nums.map(n => n * 2);
// [2, 4, 6]

// Extract property
const names = users.map(u => u.name);

// Filter array
const nums = [1, 2, 3, 4, 5];
const evens = nums.filter(n => n % 2 === 0);
// [2, 4]

// Filter objects
const adults = users.filter(u => u.age >= 18);

// Sum array
const nums = [1, 2, 3, 4];
const sum = nums.reduce((acc, n) => acc + n, 0);
// 10

// Count occurrences
const count = items.reduce((acc, item) => {
    acc[item] = (acc[item] || 0) + 1;
    return acc;
}, {});

// Find first match
const found = nums.find(n => n > 2);
const index = nums.findIndex(n => n > 2);

// Find object
const user = users.find(u => u.id === 5);

// Check if some match
const hasEven = nums.some(n => n % 2 === 0);

// Check if all match
const allPositive = nums.every(n => n > 0);

// Sort numbers
const nums = [3, 1, 4, 1, 5];
nums.sort((a, b) => a - b);

// Sort objects
users.sort((a, b) => a.age - b.age);

// Flatten nested array
const nested = [[1, 2], [3, 4]];
const flat = nested.flat();
// [1, 2, 3, 4]

// FlatMap
const arr = [1, 2, 3];
arr.flatMap(n => [n, n * 2]);