let salary = 1000000000000;

let salary = 1_000_000_000_000;

- Shipping in Chrome 75

- Transpilers like Babel support it

const array = [1, [2, [3]]];

array.flat();     // [1, 2, [3]]

array.flat(1);   // [1, 2, [3]]

array.flat(Infinity);    // [1, 2, 3]

let text = ["I do love", "JavaScript."];

let mapped = text.map(currentElement => currentElement.split(" "));

let flattened = mapped.flat();

// [["I", "do", "love"], ["JavaScript."]]

// ["I", "do", "love", "JavaScript."]

let mappedAndFlattened = text.map(currentElement => currentElement.split(" ")).flat();

// ["I", "do", "love", "JavaScript."]

🐌

let text = ["I do love", "JavaScript."];

let mappedAndFlattened = text.flatMap(currentElement => currentElement.split(" "));

// ["I", "do", "love", "JavaScript."]

🚀

Browser, Node.js, JavaScript Engine Shell

const getGlobalThis = () => {
  if (typeof self !== "undefined") return self;
  if (typeof window !== "undefined") return window;
  if (typeof global !== "undefined") return global;
  if (typeof this !== "undefined") return this;
  throw new Error("Unable to locate global object");
};

- Browsers: window

- Web/Service Workers: window is not available, so check for self

- Node: global

- Stand-alone JavaScript Shells: those don't work, so fall back to this

❌Outside of Browsers within Modules: don't run in the global scope

❌Strict mode functions: this is undefined

❌Bundlers wrap source code: this might refer to something else

const students = [
  {name: "Alex", mark: 7},
  {name: "Anda", mark: 10},

  {name: "Gabi", mark: 9},

  {name: "Ioan", mark: 8},

  {name: "Vlad", mark: 10},

];

students.sort((a, b) =>

b.mark – a.mark);

const students = [
  {name: "Anda", mark: 10},
  {name: "Vlad", mark: 10},

  {name: "Gabi", mark: 9},

  {name: "Ioan", mark: 8},

  {name: "Alex", mark: 7},

];

const students = [
  {name: "Vlad", mark: 10},
  {name: "Anda", mark: 10},

  {name: "Gabi", mark: 9},

  {name: "Ioan", mark: 8},

  {name: "Alex", mark: 7},

];

Array sort is now stable

Two new proposals are making their way through the standardisation process

76

Nightly

Polyfill

(Early stages of standardisation)

only after all the original promises have settled, i.e. become either fulfilled or rejected
(i.e. all work is done) (does not short-circuit)

as soon as one of the promises fulfilled; does not reject early when one of the promises rejects
(short-circuits when an input value is fulfilled)