New ES Edition

Optional Chaining Operator

Instead of causing an error if a reference is nullish (null or undefined), the expression short-circuits with a return value of undefined

const adventurer = {
  name: 'Alice',
  cat: {
    name: 'Dinah'
  }
};

const dogName = adventurer.dog?.name;
console.log(dogName); // undefined
console.log(adventurer.dog.name) 
// Uncaught TypeError: Cannot read property 'name' of undefined

Nullish Coalescing Operator

a logical operator that returns its right-hand side operand when its left-hand side operand is null or undefined, and otherwise returns its left-hand side operand. This can be contrasted with the logical OR (||) operator, which returns the right-hand side operand if the left operand is any falsy value, not only null or undefined.

const foo = null ?? 'default string';
console.log(foo);
// expected output: "default string"

const foo2 = null || 'default string';
console.log(foo2);
// expected output: "default string"

const baz = 0 ?? 42;
console.log(baz);
// expected output: 0

const baz2 = 0 || 42;
console.log(baz2);
// expected output: 42

Globalthis

globalThis is the universal that was previously use in browser as (window. ) 
and in terminal as (global. )

type:module

put type:module inside package.json to use import, export syntax in node