Arrays and Objects

Arrays

javascript
const arr = [1, 2, 3];
arr.push(4);
arr.length;   // 4
arr[0];       // 1
arr.pop();    // removes and returns last

Methods: map, filter, reduce, find, includes, slice, splice.

javascript
const doubled = arr.map(x => x * 2);
const evens = arr.filter(x => x % 2 === 0);
const sum = arr.reduce((acc, x) => acc + x, 0);

Objects

javascript
const user = { name: \"Alice\", age: 25 };
user.name;        // Alice
user[\"age\"];     // 25
user.city = \"NYC\";

Iterate: Object.keys(user), Object.values(user), Object.entries(user).

Destructuring

javascript
const [a, b] = [1, 2];
const { name, age } = user;