let + const { let string = 'Lorem Ipsum'; } console.log(string); // => string is not defined const PI = 3.14; PI = 3.1415; // => PI has already been declared
Set + WeakSet let array = []; let object = []; let set = new Set(); set.add('string value'); set.add(object); console.log(set.has(array)); // => false console.log(set.has(object)); // => true
Map + WeakMap let array = []; let object = []; let map = new Map(); map.set(array, 'value for array'); map.set(object, 'value for object'); console.log(map.get(array)); // => value for array console.log(map.get(object)); // => value for object
Exponentiation let squared = 2 ** 2; // same as: 2 * 2 let cubed = 2 ** 3; // same as: 2 * 2 * 2 let a = 2; a **= 2; // same as: a = a * a; let b = 3; b **= 3; // same as: b = b * b * b;