Check JavaScript Version

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JavaScript lacks a version number due to its ECMAScript basis, with engines implementing features independently. Instead of version-checking, use feature detection, or transpile code with Babel for older environments.

JavaScript, a powerful and versatile programming language, has undergone numerous changes and updates since its inception in 1995. Developers often need to consider which version their browsers are using and how to handle different versions to ensure compatibility with various features.

πŸ’‘ JavaScript is browser-dependent, meaning its version may vary across different browser types like Firefox, Chrome, or Internet Explorer.

Click on this link ( to check the JavaScript version used by your browser.

<script type="text/javascript">
  var jsver = 1.0;
<script language="Javascript1.1">
  jsver = 1.1;
<script language="Javascript1.2">
  jsver = 1.2;
<script language="Javascript1.3">
  jsver = 1.3;
<script language="Javascript1.4">
  jsver = 1.4;
<script language="Javascript1.5">
  jsver = 1.5;
<script language="Javascript1.6">
  jsver = 1.6;
<script language="Javascript1.7">
  jsver = 1.7;
<script language="Javascript1.8">
  jsver = 1.8;
<script language="Javascript1.9">
  jsver = 1.9;

<script type="text/javascript">
  alert("JavaScript version: " + jsver);

The JavaScript language has several editions known as ECMAScript, which define its syntax, features, and specifications. Additionally, JavaScript engines that execute the code may also have various versions, further complicating the matter.

This quick guide focuses on version detection techniques, keeping browser compatibility and handling incompatibilities in mind.

Browser Support

Most modern browsers support JavaScript and its various versions, including Chrome, Firefox, Safari, Opera, Internet Explorer, and Edge. 😊

Google Chrome frequently updates and stays at the cutting edge of JavaScript support, offering compatibility with the latest ECMAScript versions as they become available. The Can I use website is an excellent resource, illustrating that Chrome has a leading score in terms of JavaScript compatibility.

Similarly, Firefox is also known for staying up-to-date, offering reliable JavaScript support across its various versions.

Safari, while not as quick to adopt new JavaScript features, ensures that developers have a consistent experience, as it is based on the WebKit rendering engine. Web developers who prioritize Safari support can find detailed information on the JavaScript versions – W3Schools page.

Opera, which is based on the same underlying technologies as Chrome, shares similar JavaScript compatibility levels with Google’s browser. Thus, developers can expect consistent results across the two platforms.

When it comes to Internet Explorer and Edge, it is important to note that Edge has replaced IE as the default browser for Windows. While IE has limited support for new JavaScript features, Edge is continuously updated and offers much better support for the latest ECMAScript standards. πŸ’ͺ

Version Detection Techniques

Detecting the JavaScript version a browser supports can be useful for various reasons, such as providing the best user experience or gracefully degrading features for older browsers. In this section, we will discuss two primary techniques for version detection: User Agent String and Feature Detection.

User Agent String

The User-Agent String is a piece of text that the browser sends to the server, which includes information about the browser, operating system, and device. πŸ“

It can be used to check the browser’s JavaScript capabilities, as it typically contains information about the browser’s version. To access the User Agent String in JavaScript, you can use the navigator.userAgent property.

However, there’s a caveat: User Agent Strings can be easily spoofed, meaning they might not always provide accurate information. Thus, this method is not recommended as a reliable way to detect JavaScript versions.

Feature Detection

A more reliable and recommended approach for checking a browser’s JavaScript version is Feature Detection. πŸ˜ƒ

This technique works by testing whether a specific feature or API is available in the browser, instead of relying on the User Agent String. There are various libraries and tools available to perform feature detection, such as Modernizr and Can I Use.

Using Modernizr, you can create custom builds that check for specific features. Here’s an example of how to detect the classList feature, which can help determine if the browser supports ECMAScript 5:

if (Modernizr.classlist) {
  // Browser supports the classList feature
} else {
  // Browser does not support the classList feature

With the Can I Use website, you can quickly look up the compatibility of various browser features. This handy tool helps you determine if a feature is safe to use across different browsers. For example, you can find the compatibility chart for the classList feature mentioned above.

TLDR; Feature Detection is a more reliable and recommended method for JavaScript version detection compared to relying on User Agent Strings. By utilizing tools like Modernizr and Can I Use, you can confidently enhance your web applications with the knowledge of which JavaScript features are supported by different browsers. πŸ˜ŽπŸ’»

ECMAScript Editions

In this section, we’ll discuss the different editions of ECMAScript and their features. ECMAScript, commonly known as JavaScript, has evolved over the years, and understanding its various editions is crucial for web developers.

ES1 – ES3

The early editions of ECMAScript (ES1, ES2, and ES3) were the foundational versions that shaped the language as we know it today. ES3, released in 1999, introduced several improvements, including the RegExp object for using regular expressions and better support for manipulating strings and arrays. πŸ˜ƒ


ES5, released in 2009, was the first major update to ECMAScript after a decade-long hiatus. It brought significant advancements, such as:

  • strict mode for cleaner and safer code
  • New array methods (map, filter, reduce, etc.)
  • Enhanced object properties and support for JSON

ES6 and Later

ES6 (ECMAScript2015) took JavaScript to a new level with many modern features, making it the de facto language for web development. A few notable additions included:

  • Arrow functions: (param) => { // code }
  • Template literals: `string with ${expression} inside`
  • Destructuring assignment: const { a, b } = object
  • Default parameters: function (param = defaultValue) { // code }
  • Classes and inheritance
  • Promises for asynchronous programming
  • Modules import and export

From ES2016 and onwards, the updates to ECMAScript have been more incremental, using a yearly release cycle with new additions focused on enhancing and optimizing the language while maintaining backwards compatibility. 😎

All modern browsers fully support ES1 through ES6, allowing developers to take advantage of the latest JavaScript features with confidence. πŸš€ Know your ECMAScript version helps to utilize the features effectively and write better code.

JavaScript Engine Versions

V8 for Chrome and Node

The V8 engine is an open-source JavaScript engine developed by Google, and it powers popular browsers like Chrome 🌐 and the Node.js runtime environment βš™οΈ. It implements the ECMAScript standard as specified in ECMA-262. The engine is known for its efficient performance, making the execution of JavaScript code fast πŸ’¨.

Examples of using V8 for different environments:

  • For Chrome browser, you can check the script version using the navigator.userAgent property: console.log("Browser JavaScript engine:", navigator.userAgent);
  • For Node.js, you can check process.versions: console.log("Node.js JavaScript engine:", process.versions);

Keep in mind that feature detection is a more reliable method for detection, as you might use different JavaScript features based on the available support.

For instance, you can test for Promises support like this:

if (typeof Promise !== "undefined") {
  console.log("Promises are supported! πŸ˜ƒ");
} else {
  console.log("No Promises support 😞");

Chakra for Internet Explorer

Chakra is the JavaScript engine that powers Internet Explorer (IE) πŸ”. Just like V8, it also follows the ECMA-262 standard. While not as efficient as V8, Chakra played a vital role in the development of the web, especially during the times when Internet Explorer was the dominant browser.

To check the JavaScript version in Internet Explorer, you can use the navigator.userAgent property:

console.log("Internet Explorer JavaScript engine:", navigator.userAgent);

As mentioned earlier, using feature detection is a preferable approach, since browsers may support different JavaScript features based on their version and support:

if ("querySelector" in document) {
  console.log("querySelector is supported! πŸŽ‰");
} else {
  console.log("No querySelector support πŸ˜”");

Remember to use the information about JavaScript engines and versions wisely, keeping the focus on feature detection for a smooth and seamless browsing experience for your users! πŸ‘©β€πŸ’»πŸ‘¨β€πŸ’»

Handling Browser Incompatibilities

Dealing with browser incompatibilities is an essential part of modern web development. When working with JavaScript, you might encounter situations where your code may not run as expected in certain browsers due to differences in their JavaScript engine or support for certain features.

In this section, we will discuss two common methods for handling browser incompatibilities: Polyfills and Transpiling with Babel.


Polyfills are pieces of code that provide functionality that’s lacking in some browsers. For instance, if you’re using a modern JavaScript feature that’s not supported in older browsers, a polyfill can mimic the feature so your code runs smoothly without issues. πŸ˜ƒ

Here’s an example: The Array.prototype.includes() method is not supported in Internet Explorer (IE). To ensure your code works in IE, you can include a polyfill that adds the includes() functionality to the Array.prototype when it’s not already present.

if (!Array.prototype.includes) {
  Array.prototype.includes = function(element) {
    // Implementation of the includes method

Using polyfills can help you maintain compatibility across different browser versions, ensuring that your users have a consistent experience. Remember to only include polyfills for the features you’re actually using in your project to keep your codebase clean and download times minimal.

Transpiling with Babel

Another approach to handling browser incompatibilities is using a tool like Babel to transpile your JavaScript code from modern syntax to older, more widely supported syntax. By doing so, you can write code using the latest features and let Babel take care of generating code that will work across different browsers.

To set up Babel in your development environment, follow these steps:

  1. Install Babel: Run npm install --save-dev @babel/core @babel/cli @babel/preset-env in your project’s root directory.
  2. Create a Babel configuration file: Add a .babelrc file in your project’s root directory with the following content: { "presets": ["@babel/preset-env"] }
  3. Run Babel: Use the command npx babel src -d dist to transpile the JavaScript code in your src directory to compatible code in the dist directory.

With Babel in place, your modern JavaScript code will be parsed and transpiled to syntax that’s compatible with a wide range of browsers. This ensures that your users have a seamless experience, regardless of the browser they’re using. πŸ‘

During the development process, using an editor with code linting support can save you time by spotting potential compatibility issues before they become a problem. As part of your workflow, incorporate steps like fixing linting errors and thoroughly testing your code to further minimize browser incompatibilities.

By implementing polyfills and transpiling with Babel, you can confidently develop JavaScript projects without worrying about browser incompatibilities, creating a more enjoyable experience for your users. πŸš€

JavaScript Version in Development

JavaScript has come a long way since its creation by Brendan Eich in 1995. Throughout the years, various versions have been introduced, making it essential for developers to identify the version they’re using for their projects. πŸ“š

In the early days, JavaScript used to be referred to as “JScript” in Internet Explorer. This created compatibility challenges for developers, as each browser had slightly different implementations. However, with the rise of modern browsers like Google Chrome and other Chromium-based browsers, JavaScript has become more standardized and easier to work with. 🌐

When developing your project, a useful tutorial can be a great starting point. Keep in mind that JavaScript is an ever-evolving language, and new features continue to be introduced regularly. The ECMAScript standard governs these updates and can help you determine the appropriate version for your project. πŸ˜ƒ

To find out which version of JavaScript your browser supports, you can use the process.versions command within Node.js, as shown in this Stack Overflow example. This command will provide you with an output detailing the supported versions for your environment. πŸ› οΈ

Nowadays, it’s important to be aware that Internet Explorer has been phased out in favor of Microsoft Edge. Edge, being a Chromium-based browser, supports the majority of JavaScript features in line with other modern browsers. So even if you encounter a tutorial mentioning Internet Explorer, you can confidently work within Edge or Google Chrome to complete the exercises. πŸ’»

Frequently Asked Questions

How can I determine the JavaScript version of a website?

To determine the JavaScript version of a website, you can inspect the source code to see if it contains a specific ECMAScript version declaration or check the features used in the code. However, since JavaScript is often transpiled to compatible versions for various browsers, it might be difficult to pinpoint the exact version in use. 🧐

What methods are available to check JavaScript version in my code?

You can use feature detection to check the JavaScript version in your code. Test for the availability of certain features or methods, such as Array.prototype.includes (ES6) or Object.assign (ES5). Another approach is to use JSFiddle or a similar online code editor to deduce the version by analyzing different script tags and browsers. This Stack Overflow discussion provides more insight. πŸ•΅οΈ

How do I find out the JavaScript version used in Eclipse?

In Eclipse, the JavaScript version used depends on the project settings. Check the JavaScript version by right-clicking the project folder, selecting “Properties”, and navigating to “JavaScript>Compiler”. You can set the desired ECMAScript version from the drop-down menu. πŸ› οΈ

What is the process to check JavaScript version in Visual Studio Code?

In Visual Studio Code, the JavaScript version is determined by the TypeScript version used for type-checking. You can configure your workspace settings to use a specific TypeScript version for better compatibility. For more details, refer to the Visual Studio Code documentation. πŸ”§

What are the latest version updates in JavaScript?

JavaScript updates come through periodically with new ECMAScript releases. The most recent major update is ECMAScript 2020 (ES11), which includes features like optional chaining, nullish coalescing, and BigInt support. You can check the official ECMAScript website for the latest version information. πŸ“œ

How can I check ECMAScript version in an Angular project?

In an Angular project, the ECMAScript version is usually configured in the tsconfig.json or file. Look for the property, which specifies the ECMAScript version the TypeScript compiler produces. For example, "target": "es2015" indicates that the Angular project is using ECMAScript 2015 (ES6). πŸ”