What are the new features in ES6?

ES6 (ECMAScript 2015) Key Features

1. let and const

Block-scoped alternatives to var.

let count = 0;
const MAX = 100;

2. Arrow Functions

const add = (a, b) => a + b;

3. Template Literals

const name = 'Alice';
console.log(`Hello, ${name}!`);

4. Destructuring Assignment

const [a, b] = [1, 2];
const { name, age } = { name: 'Bob', age: 25 };

5. Default Parameters

function greet(name = 'World') {
  return `Hello, ${name}!`;
}

6. Spread / Rest Syntax

const arr = [1, 2, 3];
const newArr = [...arr, 4, 5]; // spread

function sum(...nums) {         // rest
  return nums.reduce((a, b) => a + b, 0);
}

7. Classes

class Animal {
  constructor(name) { this.name = name; }
  speak() { console.log(this.name); }
}
class Dog extends Animal {}

8. ES Modules

export const PI = 3.14;
export default function add(a, b) { return a + b; }

import add, { PI } from './math.js';

9. Promises

fetch('/api/data')
  .then(res => res.json())
  .catch(err => console.error(err));

10. Symbol

const id = Symbol('id');

11. Map and Set

const map = new Map();
const set = new Set([1, 2, 3]);

12. for...of Loop

for (const item of [1, 2, 3]) {
  console.log(item);
}

13. Object Shorthand

const name = 'Alice';
const obj = { name, greet() { return 'hi'; } };

14. Iterators and Generators

function* gen() {
  yield 1;
  yield 2;
}