Fixing JavaScript Compatibility Issues with Internet Explorer

JavaScript is a widely used scripting language that allows web developers to add interactive and dynamic content to websites. While JavaScript works well with modern browsers like Google Chrome, Mozilla Firefox, and Safari, it sometimes runs into compatibility issues with older versions of Internet Explorer (IE). This can lead to a frustrating experience for both developers and users, as the site may not work as intended or look visually appealing. This blog post will provide you with a comprehensive guide on how to fix JavaScript compatibility issues with Internet Explorer, enabling you to create websites that work seamlessly across all browsers.

Understanding the Problem

Before diving into the solutions, it's essential to understand why JavaScript compatibility issues arise with Internet Explorer. IE has a history of not adhering to web standards, and this non-compliance results in inconsistencies in how JavaScript is interpreted and executed. Additionally, IE lacks support for many modern JavaScript features, which can cause errors or unexpected behavior when running scripts. By addressing these issues, you can ensure that your website works smoothly for all users, regardless of the browser they use.

Using Polyfills

Polyfills are JavaScript libraries that provide modern functionality in older browsers that don't natively support them. They can help bridge the gap between your code and the limitations of Internet Explorer. By including polyfills in your project, you can use modern JavaScript features without worrying about compatibility issues.

Popular Polyfills

Here are some popular polyfills that you can use in your project:

  1. Babel: Babel is a popular JavaScript compiler that can transpile your code to a version compatible with older browsers, like Internet Explorer. To use Babel, you need to install it and configure it to target specific browser versions.
  2. core-js: core-js is a modular library that provides polyfills for various ECMAScript features, including those not supported by Internet Explorer. You can use it alongside Babel to ensure your code is compatible with older browsers.
  3. fetch: The fetch polyfill adds support for the Fetch API, which is not available in Internet Explorer. Including this polyfill will allow you to use the modern Fetch API across all browsers.

How to Use Polyfills

To use a polyfill, simply include the relevant script in your project, either by downloading and hosting it yourself or by using a CDN (Content Delivery Network) link. For example, to use the fetch polyfill, include the following code in the head of your HTML file:

<script src="https://cdnjs.cloudflare.com/ajax/libs/fetch/3.0.0/fetch.min.js"></script>

Conditional Comments and Feature Detection

Conditional comments are a feature of Internet Explorer that allows you to target specific versions of IE with specific code. You can use them to apply fixes or workarounds to your JavaScript code that are only necessary for certain versions of Internet Explorer.

To use conditional comments, enclose the relevant code within <!--[if IE]> and <![endif]--> tags. For example, to include a script only for Internet Explorer 9, you would use the following conditional comment:

<!--[if IE 9]> <script src="path/to/ie9-fix.js"></script> <![endif]-->

In addition to conditional comments, you can use feature detection to determine whether a specific feature is supported by the user's browser. This can help you provide alternative implementations or fallbacks for unsupported features. For example, you can use the following code to detect if the browser supports the classList property:

if ('classList' in document.documentElement) { // The browser supports classList } else { // The browser does not support classList, provide a fallback }

Utilizing Libraries and Frameworks

Usingpopular libraries and frameworks can help you write JavaScript code that is compatible with Internet Explorer. These libraries often include built-in support for older browsers, which saves you the time and effort of writing custom fixes.


jQuery is a popular JavaScript library that simplifies tasks such as DOM manipulation, event handling, and AJAX. Since jQuery is compatible with Internet Explorer 6 and above, you can use it to create cross-browser compatible code.

To use jQuery, include the following script tag in the head of your HTML file:

<script src="https://code.jquery.com/jquery-3.6.0.min.js"></script>

Then, you can use jQuery to manipulate the DOM or handle events in a way that is compatible with Internet Explorer. For example, instead of using document.querySelector, you can use the jQuery $ function:

// With vanilla JavaScript var element = document.querySelector('.my-element'); // With jQuery var element = $('.my-element');


Modernizr is a JavaScript library that detects the availability of specific HTML5 and CSS3 features in the user's browser. It can help you identify unsupported features and apply fallbacks or workarounds as needed.

To use Modernizr, include the following script tag in the head of your HTML file:

<script src="https://cdnjs.cloudflare.com/ajax/libs/modernizr/2.8.3/modernizr.min.js"></script>

You can then use the Modernizr object to check for feature support. For example, you can use the following code to detect if the browser supports the querySelector method:

if (Modernizr.querySelector) { // The browser supports querySelector } else { // The browser does not support querySelector, provide a fallback }

CSS Fixes for Internet Explorer

JavaScript compatibility is not the only concern when it comes to Internet Explorer. You might also encounter issues with your CSS. To address these issues, you can use conditional comments to target specific IE versions and apply the necessary CSS fixes.

For example, to include a stylesheet only for Internet Explorer 9, you would use the following conditional comment:

<!--[if IE 9]> <link rel="stylesheet" href="path/to/ie9-fix.css"> <![endif]-->

Inside the ie9-fix.css file, you can apply the required CSS fixes that are specific to Internet Explorer 9.


Q: Why is my JavaScript code not working in Internet Explorer?

A: There could be several reasons for this, such as using features not supported by Internet Explorer, syntax errors in your code, or differences in the way IE interprets JavaScript. To resolve these issues, consider using polyfills, conditional comments, feature detection, and popular libraries or frameworks.

Q: Which versions of Internet Explorer should I support?

A: The answer depends on your target audience and their browser usage. However, as of January 2020, Microsoft has ended support for all versions of Internet Explorer except for IE 11. It is generally recommended to support IE 11, and possibly IE 9 and 10, depending on your user base.

Q: Can I use ES6 (ECMAScript 2015) features in Internet Explorer?

A: Internet Explorer does not natively support many ES6 features. However, you can use a tool like Babel to transpile your ES6 code into ES5, which is compatible with older browsers like Internet Explorer.

Q: Is it necessary to make my website compatible with Internet Explorer?

A: This decision depends on your target audience and their browser usage. However, considering the declining market share of Internet Explorer and Microsoft's pushtowards its newer browser, Microsoft Edge, it is becoming less critical to support Internet Explorer. That being said, it is essential to evaluate your website's analytics data to determine the percentage of users accessing your site using Internet Explorer. If a significant portion of your users still relies on IE, then it is worth making your website compatible with it.

Q: Can I use CSS Grid or Flexbox in Internet Explorer?

A: Internet Explorer has limited support for Flexbox (supported in IE 10+ with vendor prefixes) and does not support CSS Grid (supported in Microsoft Edge 16+). If you need to use these modern layout techniques while maintaining compatibility with Internet Explorer, consider using a library like Autoprefixer to handle vendor prefixes or employing feature detection to provide fallback styles for unsupported browsers.


Ensuring that your JavaScript code is compatible with Internet Explorer can be challenging, but it is achievable through a combination of polyfills, conditional comments, feature detection, and the use of popular libraries and frameworks. By following the guidance and best practices provided in this blog post, you can create a seamless browsing experience for your users, regardless of the browser they use.

Remember to continually evaluate your target audience and their browser usage, as supporting older browsers may become less necessary over time. It is essential to strike a balance between providing compatibility for older browsers and embracing modern web development techniques that improve the overall user experience.

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