ECMAScript 6 (ES6) enhancements to the JavaScript language

ECMAScript 6 (also known as ES6 or ECMAScript 2015) is a version of JavaScript that introduced several new features to the language. Here are a few examples:

• let and const: ES6 introduced two new ways to declare variables: let and const. let is similar to the var keyword, but variables declared with let are block-scoped, rather than function-scoped. const is used to declare variables that cannot be reassigned.
• Arrow Functions: ES6 introduced a new shorthand syntax for defining functions, called arrow functions. Arrow functions have a more concise syntax and their this keyword lexically bound.

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

• Template literals: ES6 introduced a new way to create strings that include variables, called template literals. These use backticks () instead of single or double quotes, and variables are denoted by a dollar sign and curly braces (${}`)

let name = "John";
console.log(`Hello, ${name}!`); 

let [a, b, c] = [1, 2, 3]; 
let {x, y, z} = {x: 1, y: 2, z: 3}; 

• Classes: ES6 introduced a new way to define classes, similar to those in other object-oriented languages.

class Person {
   constructor(name) {
     this.name = name;
   }
   sayHello() {
     console.log("Hello, my name is " + this.name);   
} } 

• Modules: ES6 introduced a new way to organize and reuse code, called modules. Modules allow you to define a set of exports (variables, functions, classes, etc.) that can be imported into other files.

// myModule.js 
export let x = 1;
export function add(a, b) {
   return a + b; 
} 
// main.js
import {x, add} from "./myModule.js";
console.log(x); // 1
console.log(add(1, 2)); // 3 

These are just a few examples; many more features are introduced in ES6, such as Promises, Symbol, Generators, etc.