Menu
×
   ❮     
HTML CSS JAVASCRIPT SQL PYTHON JAVA PHP HOW TO W3.CSS C C++ C# BOOTSTRAP REACT MYSQL JQUERY EXCEL XML DJANGO NUMPY PANDAS NODEJS R TYPESCRIPT ANGULAR GIT POSTGRESQL MONGODB ASP AI GO KOTLIN SASS VUE DSA GEN AI SCIPY AWS CYBERSECURITY DATA SCIENCE
     ❯   

JS Tutorial

JS HOME JS Introduction JS Where To JS Output JS Statements JS Syntax JS Comments JS Variables JS Let JS Const JS Operators JS Arithmetic JS Assignment JS Data Types JS Functions JS Objects JS Object Properties JS Object Methods JS Object Display JS Object Constructors JS Events JS Strings JS String Methods JS String Search JS String Templates JS Numbers JS BigInt JS Number Methods JS Number Properties JS Arrays JS Array Methods JS Array Search JS Array Sort JS Array Iteration JS Array Const JS Dates JS Date Formats JS Date Get Methods JS Date Set Methods JS Math JS Random JS Booleans JS Comparisons JS If Else JS Switch JS Loop For JS Loop For In JS Loop For Of JS Loop While JS Break JS Iterables JS Sets JS Set Methods JS Maps JS Map Methods JS Typeof JS Type Conversion JS Destructuring JS Bitwise JS RegExp JS Precedence JS Errors JS Scope JS Hoisting JS Strict Mode JS this Keyword JS Arrow Function JS Classes JS Modules JS JSON JS Debugging JS Style Guide JS Best Practices JS Mistakes JS Performance JS Reserved Words

JS Versions

JS Versions JS 2009 (ES5) JS 2015 (ES6) JS 2016 JS 2017 JS 2018 JS 2019 JS 2020 JS 2021 JS 2022 JS 2023 JS 2024 JS IE / Edge JS History

JS Objects

Object Definitions Object Prototypes Object Methods Object Properties Object Get / Set Object Protection

JS Functions

Function Definitions Function Parameters Function Invocation Function Call Function Apply Function Bind Function Closures

JS Classes

Class Intro Class Inheritance Class Static

JS Async

JS Callbacks JS Asynchronous JS Promises JS Async/Await

JS HTML DOM

DOM Intro DOM Methods DOM Document DOM Elements DOM HTML DOM Forms DOM CSS DOM Animations DOM Events DOM Event Listener DOM Navigation DOM Nodes DOM Collections DOM Node Lists

JS Browser BOM

JS Window JS Screen JS Location JS History JS Navigator JS Popup Alert JS Timing JS Cookies

JS Web APIs

Web API Intro Web Forms API Web History API Web Storage API Web Worker API Web Fetch API Web Geolocation API

JS AJAX

AJAX Intro AJAX XMLHttp AJAX Request AJAX Response AJAX XML File AJAX PHP AJAX ASP AJAX Database AJAX Applications AJAX Examples

JS JSON

JSON Intro JSON Syntax JSON vs XML JSON Data Types JSON Parse JSON Stringify JSON Objects JSON Arrays JSON Server JSON PHP JSON HTML JSON JSONP

JS vs jQuery

jQuery Selectors jQuery HTML jQuery CSS jQuery DOM

JS Graphics

JS Graphics JS Canvas JS Plotly JS Chart.js JS Google Chart JS D3.js

JS Examples

JS Examples JS HTML DOM JS HTML Input JS HTML Objects JS HTML Events JS Browser JS Editor JS Exercises JS Quiz JS Website JS Interview Prep JS Bootcamp JS Certificate

JS References

JavaScript Objects HTML DOM Objects


ECMAScript 2022

JavaScript Version Numbers

Old ECMAScript versions was named by numbers: ES5 and ES6.

From 2016, versions are named by year: ES2016, 2018, 2020, 2022.

New Features in ES2022


Warning

These features are relatively new.

Older browsers may need an alternative code (Polyfill)


JavaScript Array at()

ES2022 intoduced the array method at():

Examples

Get the third element of fruits:

const fruits = ["Banana", "Orange", "Apple", "Mango"];
let fruit = fruits.at(2);
Try it Yourself »

Get the third element of fruits:

const fruits = ["Banana", "Orange", "Apple", "Mango"];
let fruit = fruits[2];
Try it Yourself »

The at() method returns an indexed element from an array.

The at() method returns the same as [].

The at() method is supported in all modern browsers since March 2022:

Chrome 92 Edge 92 Firefox 90 Safari 15.4 Opera 78
Apr 2021 Jul 2021 Jul 2021 Mar 2022 Aug 2021

Note

Many languages allows negative bracket indexing like [-1] to access elements from the end of an object / array / string.

This is not possible in JavaScript, because [] is used for accessing both arrays and objects. obj[-1] refers to the value of key -1, not to the last property of the object.

The at() method was introduced in ES2022 to solve this problem.


JavaScript String at()

ES2022 intoduced the string method at():

Examples

Get the third letter of name:

const name = "W3Schools";
let letter = name.at(2);
Try it Yourself »

Get the third letter of name:

const name = "W3Schools";
let letter = name[2];
Try it Yourself »

The at() method returns an indexed element from an string.

The at() method returns the same as [].

The at() method is supported in all modern browsers since March 2022:

Chrome 92 Edge 92 Firefox 90 Safari 15.4 Opera 78
Apr 2021 Jul 2021 Jul 2021 Mar 2022 Aug 2021

RegExp d Modifier

ES2022 added the /d modifier to express the start and end of the match.

Example

let text = "aaaabb";
let result = text.match(/(aa)(bb)/d);
Try it Yourself »

RegExp Modifiers are used to spescfy case-insensitive, and other global searches:

Modifier Description Try it
i Perform case-insensitive matching Try it »
g Perform a global match (find all) Try it »
m Perform multiline matching Try it »
d Perform substring matches (New in ES2022) Try it »

Object hasOwn

ES2022 provides a safe way to check if a property is the own property of an object.

Object.hasOwn() is similar to Object.prototype.hasOwnProperty but supports all object types.

Example

Object.hasOwn("initProp")
Try it Yourself »

Error Cause

ES2022 let you specify the reason behind an error with error.cause.

Example

try { connectData(); } catch (err) { throw new Error("Connecting failed.", { cause: err }); }
Try it Yourself »


JavaScript await import

JavasSript modules can now wait for resources that require import before running:

import {myData} from './myData.js';

const data = await myData();

JavaScript Class Field Declarations

class Hello {
  counter = 0; // Class field
}
const myClass = new Hello();

let x = myClass.counter;

Class Field Declarations is supported in all modern browsers since April 2021:

Chrome 72 Edge 79 Firefox 69 Safari 14.1 Opera 60
Jan 2019 Jan 2020 Sep 2019 Apr 2021 Jan 2020

JavaScript Private Methods and Fields

class Hello {
  #counter = 0;  // Private field
  #myMethod() {} // Private method
}
const myClass = new Hello();

let x = myClass.#counter; // Error
myClass.#myMethod();      // Error

Private Methods and Fields is supported in all modern browsers since June 2021:

Chrome 74 Edge 79 Firefox 90 Safari 14.1 Opera 62
Apr 2019 Jan 2020 Jun 2021 Apr 2021 Jun 2019


×

Contact Sales

If you want to use W3Schools services as an educational institution, team or enterprise, send us an e-mail:
[email protected]

Report Error

If you want to report an error, or if you want to make a suggestion, send us an e-mail:
[email protected]

W3Schools is optimized for learning and training. Examples might be simplified to improve reading and learning. Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content. While using W3Schools, you agree to have read and accepted our terms of use, cookie and privacy policy.

Copyright 1999-2024 by Refsnes Data. All Rights Reserved. W3Schools is Powered by W3.CSS.