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 DSA TYPESCRIPT ANGULAR GIT POSTGRESQL MONGODB ASP AI R GO KOTLIN SASS VUE GEN AI SCIPY CYBERSECURITY DATA SCIENCE INTRO TO PROGRAMMING BASH RUST

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 Sets JS Set Methods JS Set Logic JS Maps JS Map Methods JS Typed Arrays JS Typed Methods JS Iterables JS Iterators JS typeof JS toString() 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 2025 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 Validation 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 Syllabus JS Study Plan JS Interview Prep JS Bootcamp JS Certificate

JS References

JavaScript Objects HTML DOM Objects


ECMAScript 2025

Warning

These features are relatively new.

Older browsers may need an alternative code (Polyfill)


The RegExp.escape() Method

The RegExp.escape() method returns a string where characters that belongs to the regular expression syntax are escaped.

This makes it possible to treat characters like +, *, ?, ^, $, (, ), [, ], {, }, |, and \ literally, and not as part of a regular expression.

Example

Create a regular expression that matches the string "[*]":

// Escape a text for to use as a regular expression
const safe = RegExp.escape("[*]";

// Build a new reglar expression
const regex = new RegExp(safe);

// Text to replace within
const oldText = "[*] is a web school.";

// Perform the replace
const newText = oldText.match(regex, "W3Schools");
Try it Yourself »

RegExp.escape() is supported all in modern browsers since May 2025:

Chrome 136 Edge 136 Firefox 134 Safari 18.2 Opera 121
Apr 2025 May 2025 Jan 2025 Des 2024 Jun 2025

Modules with Import Attributes

Syntax

import {names} from "module-name" with {key:"data"};

Examples

import config from "config.json" with {type:"json"};

import styles from "styles.css" with {type:"css"};

import data from "data.json" with {type:"json"};

Float16Array (Half-Precision-Float)

A Float16Array is a TypedArray that stores 16-bit (half-precision) floating-point numbers in the IEEE 754 half-precision format.

Float16Array requires half the memory of Float32Array and a quarter of Float64Array.

Example

const myArr = new Float16Array([1.5, 2.5, 3.5, 4.5]);

let bytes = myArr.BYTES_PER_ELEMENT;
let length = myArr.length;
Try it Yourself »

The Float16Array object is supported in all modern browsers since June 2024:

Chrome 135 Edge 135 Firefox 129 Safari 18.2 Opera 120
Apr 2025 Apr 2025 Aug 2024 Des 2024 May 2025

JavaScript Set union()

The union() method returns the union of two sets.

The union() method returns a new set containing the elements which are in this set, or in the argument set, or in both:

Union

Example

const A = new Set(['a','b','c']);
const B = new Set(['b','c','d']);

const C = A.union(B);
Try it Yourself »

The union() method is supported in all modern browsers since June 2024:

Chrome 122 Edge 122 Firefox 127 Safari 17 Opera 108
Feb 2024 Feb 2024 Jun 2024 Sep 2023 Mar 2024

JavaScript Set intersection()

The intersection() method returns the intersection of two sets.

The intersection() method returns a new set containing the elements which are in this set and in the argument set:

Intersection

Example

const A = new Set(['a','b','c']);
const B = new Set(['b','c','d']);

const C = A.intersection(B);
Try it Yourself »

The intersection() method is supported in all modern browsers since June 2024:

Chrome 122 Edge 122 Firefox 127 Safari 17 Opera 108
Feb 2024 Feb 2024 Jun 2024 Sep 2023 Mar 2024

JavaScript Set difference()

The difference() method returns the difference between two sets.

The difference() method returns a new set containing elements which are in this set but not in the argument set:

Difference

Example

const A = new Set(['a','b','c']);
const B = new Set(['b','c','d']);

const C = A.difference(B);
Try it Yourself »

The difference() method is supported in all modern browsers since June 2024:

Chrome 122 Edge 122 Firefox 127 Safari 17 Opera 108
Feb 2024 Feb 2024 Jun 2024 Sep 2023 Mar 2024

JavaScript Set symmetricDifference()

The symmetricDifference() method returns the symmetric difference between to sets.

The symmetricDifference() method returns a new set containing elements which are in this set or in the argument set, but not in both:

Symmetric Difference

Example

const A = new Set(['a','b','c']);
const B = new Set(['b','c','d']);

const C = A.symetricDifference(B);
Try it Yourself »

The symmetricDifference() method is supported in all modern browsers since June 2024:

Chrome 122 Edge 122 Firefox 127 Safari 17 Opera 108
Feb 2024 Feb 2024 Jun 2024 Sep 2023 Mar 2024

JavaScript Set isSubsetOf()

The isSubsetOf() method returns true if all elements in this set are elements in the argument set:

Subset

Example

const A = new Set(['a','b','c']);
const B = new Set(['b','c','d']);

let answer = A.isSubsetOf(B);
Try it Yourself »

The isSubsetOf() method is supported in all modern browsers since June 2024:

Chrome 122 Edge 122 Firefox 127 Safari 17 Opera 108
Feb 2024 Feb 2024 Jun 2024 Sep 2023 Mar 2024

JavaScript Set isSupersetOf()

The isSupersetOf() method returns true if all elements in the argument set are also in this set:

Superset

Example

const A = new Set(['a','b','c']);
const B = new Set(['b','c','d']);

let answer = A.isSupersetOf(B);
Try it Yourself »

The isSupersetOf() method is supported in all modern browsers since June 2024:

Chrome 122 Edge 122 Firefox 127 Safari 17 Opera 108
Feb 2024 Feb 2024 Jun 2024 Sep 2023 Mar 2024

JavaScript Set isDisjointFrom()

The isDisjointFrom() method returns true if this set has no elements in common with the argument set:

Disjoint

Example

const A = new Set(['a','b','c']);
const B = new Set(['b','c','d']);

let answer = A.isDisjointFrom(B);
Try it Yourself »

The Set.isDisjointFrom() method is supported in all modern browsers since June 2024:

Chrome 122 Edge 122 Firefox 127 Safari 17 Opera 108
Feb 2024 Feb 2024 Jun 2024 Sep 2023 Mar 2024


×

Contact Sales

If you want to use W3Schools services as an educational institution, team or enterprise, send us an e-mail:
sales@w3schools.com

Report Error

If you want to report an error, or if you want to make a suggestion, send us an e-mail:
help@w3schools.com

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 1999-2025 by Refsnes Data. All Rights Reserved. W3Schools is Powered by W3.CSS.