Основы ES6

const obj = { foo: 1 }; 

obj.bar = 2;

let name = 'Harry';

let occupation = 'wizard';

console.log(`Hi! My name is ${name}. I'm a ${occupation}.`);

(function() {

 let f = this ? class g { } : class h { };

 return [ typeof f, typeof h ];

 })();

[...[...'...']].length

typeof (new (class F extends (String, Array) { })).substring

(function() { 

if (false) {

 let f = { g() => 1 };

 }

 return typeof f;

 })()

const PI = 3.14; 

console.log(PI) // Печатает 3.14

let point = [1,3], segment = [point,[5,5]], triangle = [...segment,[1,8]];