ECMAScript 2020

New Features in JavaScript 2020

New JavaScript Operators in 2020

Browser Support

ECMAScript 2020 is supported in all modern browsers since April 2021.

JavaScript BigInt

JavaScript BigInt variables are used to store big integer values that are too big to be represented by a a normal JavaScript Number.

JavaScript integers are only accurate up to about 15 digits.

Integer Example

let x = 999999999999999;

let y = 9999999999999999; // too big

To create a BigInt, append n to the end of an integer or call BigInt():

Example

let x = 1234567890123456789012345n;

let y = BigInt(1234567890123456789012345)

The JavaScript typeof a BigInt is "bigint":

Example

let x = BigInt(999999999999999);

let type = typeof x;

JavaScript String matchAll()

Before ES2020 there was no string method that could be used to search for all occurrences of a string in a string.

Example

const iterator = text.matchAll("Cats");

If the parameter is a regular expression, the global flag (g) must be set set, otherwise a TypeError is thrown.

Example

const iterator = text.matchAll(/Cats/g);

If you want to search case insensitive, the insensitive flag (i) must be set:

Example

const iterator = text.matchAll(/Cats/gi);

The Nullish Coalescing Operator (??)

The ?? operator returns the first operand if it is not nullish. Otherwise it returns the second.

The ?? operator returns the second operand if the first operand is nullish.

Nullish is a word for describing null or undefined.

The ?? operator is used to provide default values and is distinct from the logical OR operator || because it only treats null and undefined as "nullish" and ignores other "falsy" values like 0 or an empty string.

Example

let name = null;

let text = "missing";

let result = name ?? text;

The Optional Chaining Operator (?.)

The Optional Chaining Operator returns undefined if an object property is undefined or null (instead of throwing an error).

Example

const car = {type:"Fiat", model:"500", color:"white"};

let name = car?.name;

Optional chaining not only works on object properties, but also on function calls and arrays.

Function Calls

Arrays

The &&= Operator

The Logical AND Assignment Operator is used between two values.

If the first value is true, the second value is assigned.

Logical AND Assignment Example

let x = 10;

x &&= 5;

The ||= Operator

The Logical OR Assignment Operator is used between two values.

If the first value is false, the second value is assigned.

Logical OR Assignment Example

let x = 10;

x ||= 5;

The ??= Operator

The Nullish Coalescing Assignment Operator is used between two values.

If the first value is undefined or null, the second value is assigned.

Nullish Coalescing Assignment Example

let x;

x ??= 10;

JavaScript Promise.allSettled()

The Promise.allSettled() method returns a single Promise from a list of promises.

Example

// Create a Promise

const myPromise1 = new Promise((resolve, reject) => {

  setTimeout(resolve, 200, "King");

});

// Create another Promise

const myPromise2 = new Promise((resolve, reject) => {

  setTimeout(resolve, 100, "Queen");

});

// Settle All

Promise.allSettled([myPromise1, myPromise2]).then((results) =>

  results.forEach((x) => myDisplay(x.status)),

);

JavaScript Dynamic Import

Dynamic Import is a way to load JavaScript modules at runtime, rather than at the start of your program.

Syntax

import("./module.js")

• The argument must be a string or expression that resolves to a path
• You must run the import inside a module script ( )

Unlike static imports (which must appear at the top of a file), dynamic imports can be used anywhere - inside functions, conditionals, event handlers, etc.

JavaScript Global This

globalThis provides a standard way to access the global object, regardless of the environment your the code runs in: In the browser, Node.js, in a Web Worker, or another JS runtime.

The global object is the top-level object in a JavaScript environment: - In browsers, it is window. - In Node.js, it is global. - In Web Workers, it is self. Many environments have their own name for the this object. This caused compatibility issues for code meant to run everywhere.

globalThis was introduced in ECMAScript 2020 (ES11) to solve that problem. It is a unified reference to the global object, no matter the environment.

Examples

globalThis === window); // true in browsers

globalThis === global); // true in Node.js

Previously, developers had to use workarounds like:

Example

const getGlobal = function() {

  if (typeof self !== 'undefined') return self;

  if (typeof window !== 'undefined') return window;

  if (typeof global !== 'undefined') return global;

  throw new Error('Cannot find global object');

};

With globalThis, that is no longer needed.

JavaScript import.meta

import.meta returns an object containing the base URL of a module.

Example

const myObject = import.meta;

Module Namespace Exports

With module namespace exports, you can re-export an entire namespace from your own module, without having to import it first.

Example

// re-export all named exports directly

export * from "./utils.js";

// consumers can use:

import { add } from "./math.js";