Cross-Browser Compatibility: Tips And Techniques
Published: 2023-10-13 16:26:02

by [Winner Ovunda](https://blog.openreplay.com/authors/winner-ovunda)

<blockquote><em>
Browsers are not always compatible, getting a web app to function correctly across different browsers requires special methods, and this article will show you some tips and techniques to get you started.
</em></blockquote>

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# Cross-Browser Compatibility: Tips and Techniques for Consistent Website Functionality
Cross-browser compatibility simply emphasizes the ability of a web application or website to function or operate on all browsers. In developing websites, there is a need to prioritize cross-browser compatibility, as [HTML](https://developer.mozilla.org/en-US/docs/Web/HTML), [CSS](https://developer.mozilla.org/en-US/docs/Web/CSS), and [JavaScript](https://developer.mozilla.org/en-US/docs/Web/JavaScript) are interpreted by browsers on varying terms.

Cross-browser compatibility makes it possible for websites to run on any browser. It helps to manage the time and expenses used in browser-specific coding and testing. It helps to ensure a smooth and efficient experience for all users. When a website is not cross-browser compatible, users may have challenges that impact their web experience negatively. It can result in users not wanting to make purchases or complete other actions if the website is not accessible on their preferred browser.


## Understanding Browser Differences

To create a website compatible with a wide range of browsers, developers must know their differences. This would include different features and rendering engines each browser uses and different browser versions. By understanding these differences, developers can create websites that can function on all browsers.
To understand browser differences, we would look into Browser market share and diversity, Rendering engines, and Browser versions and updates.


- Browser market share: Understanding browser market share is another important aspect of ensuring cross-browser compatibility. By knowing which browsers are most commonly used, developers can focus on ensuring compatibility with those browsers. Understanding the popularity of different browsers can be helpful to developers. In addition to knowing the market share of different browsers, it is also important to understand how the market share changes over time. For example, Chrome has gained market share over the past few years, while Firefox and Internet Explorer have declined in popularity. This trend can help developers predict which browsers will be most popular in the future and how to prioritize their compatibility efforts.


- Rendering engines: Web browsers use rendering engines to interpret and display web content, including HTML, CSS, and JavaScript. Different browsers use distinct rendering engines, each with its features and quirks. `WebKit`, Gecko, Blink, and Trident are four of the most widely used rendering engines. 
   
-    [`WebKit`](https://developer.mozilla.org/en-US/docs/Web/CSS/WebKit_Extensions) is a rendering engine created for Apple's Safari browser. Many other browsers, including Chrome have since adopted it. Thanks to features like just-in-time compilation and GPU acceleration, it is known for its speed and efficiency. It also supports CSS and HTML5 features and touch and gesture interactions. It also makes tools and APIs available for developers to create interactive and visually appealing web applications. However, It has been criticized for not being as interoperable with other rendering engines and for its closed-source code.
   
-    [Gecko](https://developer.mozilla.org/en-US/docs/Glossary/Gecko) rendering engine is an open-source project developed by Mozilla. It's the rendering engine used by the Firefox browser. It is known for its support for open web standards, including CSS and HTML5, and its ability to handle complex web applications. It has played a significant role in developing web technologies, including innovations like tabbed browsing, add-ons, and privacy enhancements. Its open-source nature has allowed developers to contribute to its development and create customized browsing experiences. As a result, It has become a popular choice among those who value privacy and customization. However, Gecko has been criticized for being slower than other rendering engines and not being as compatible with certain web technologies.


-    [Blink](https://developer.mozilla.org/en-US/docs/Glossary/Blink) is a fast and efficient rendering engine in Google Chrome and other Chromium-based browsers. It's based on the `WebKit` engine but has been rewritten for improved performance. It also supports modern web technologies like CSS Grid Layout and Flexbox, making it easier to create responsive websites. The V8 JavaScript engine is built-in, and it improves performance and reduces memory usage. It also has a GPU-accelerated rendering pipeline that uses the computer's graphics processing unit (GPU) to render pages more quickly. It is widely considered to be one of the fastest rendering engines available.


-    [Trident](https://developer.mozilla.org/en-US/docs/Glossary/Trident) rendering engine, developed by Microsoft, is used in Internet Explorer and Microsoft Edge. While it has been around for a long time and offers good compatibility with legacy web pages, it's been criticized for being slow, having non-standard behaviors, and limited support for modern web standards. As a result, it was difficult to create web pages that were compatible across different browsers. However, Microsoft's recent shift towards the Chromium engine shows a commitment to greater compatibility and adherence to web standards. Microsoft is working to improve Trident and bring it up to speed with other rendering engines. This will allow it to better compete with modern alternatives, such as Blink and WebKit. This could lead to a more consistent and streamlined web browsing experience for users.


-  Browser versions and updates: These are key factors in understanding how browsers differ and interact with the web. Vendors introduce changes to their rendering engines, features, and APIs with each new browser version and update. These changes can cause differences in how web content is rendered and interacted with across browsers. It's therefore important for developers to keep up with browser versions and updates to ensure their websites are compatible and accessible to all users.


## Key Challenges in Cross-Browser Compatibility
- Rendering disparities: When a web page is rendered, the browser converts HTML, CSS, and JavaScript code into a visual representation that the user can see and interact with. Rendering disparities occur when different browsers render the same web page differently, leading to inconsistent visual presentation. These disparities can be caused by several factors, including [CSS gradients](https://developer.mozilla.org/en-US/docs/Web/CSS/gradient), [`box-shadow`](https://developer.mozilla.org/en-US/docs/Web/CSS/box-shadow), and [`fonts`](https://developer.mozilla.org/en-US/docs/Web/CSS/font), CSS interpretation, [Box model](https://developer.mozilla.org/en-US/docs/Learn/CSS/Building_blocks/The_box_model) differences, [CSS prefixes](https://developer.mozilla.org/en-US/docs/Glossary/Vendor_Prefix#css_prefixes), CSS hacks, JavaScript executions, [Flexbox](https://developer.mozilla.org/en-US/docs/Learn/CSS/CSS_layout/Flexbox) and [`Grid`](https://developer.mozilla.org/en-US/docs/Web/CSS/grid) behavior.


- CSS inconsistencies: CSS inconsistencies between browsers are a major source of cross-browser compatibility issues. CSS styles the appearance and layout of websites and web applications, so when browsers interpret and render CSS differently, it can lead to web design and layout differences that may negatively affect the user experience. These inconsistencies may arise from differences in the way browsers handle [CSS selectors](https://developer.mozilla.org/en-US/docs/Learn/CSS/Building_blocks/Selectors), properties, [values](https://developer.mozilla.org/en-US/docs/Learn/CSS/Building_blocks/Values_and_units), and [declarations](https://developer.mozilla.org/en-US/docs/Web/API/CSSStyleDeclaration). Additionally, browser vendor prefixes for emerging CSS properties, Box model interpretation, Float behavior, and Flexbox and Grid compatibility can cause inconsistencies.


- JavaScript compatibility issues: Cross-browser compatibility is also impacted by JavaScript inconsistencies, which can arise from differences in the way browsers handle and interpret JavaScript code. These inconsistencies may cause errors or prevent features from working as intended, leading to a poor user experience. JavaScript compatibility issues are exacerbated by the fact that browsers often use different versions of JavaScript engines, such as [V8](https://v8.dev/) and [SpiderMonkey](https://spidermonkey.dev/), and may not fully support all the features of the ECMAScript standard. Other causes of this compatibility issues include, [DOM](https://developer.mozilla.org/en-US/docs/Web/API/Document_Object_Model/Introduction) manipulation, [AJAX](https://developer.mozilla.org/en-US/docs/Web/Guide/AJAX) and [Fetch API](https://developer.mozilla.org/en-US/docs/Web/API/Fetch_API/Using_Fetch), Security restrictions.


## Best Practices for Ensuring Cross-Browser Compatibility

Developers must follow certain best practices to ensure cross-browser compatibility. These practices are designed to address rendering disparities, CSS inconsistencies, and JavaScript compatibility issues, all of which can create a suboptimal user experience. The key best practices to be reviewed here are Progressive enhancement and graceful degradation, modern web standards and technologies, and Software testing on popular and relevant browsers.

### Progressive enhancement
Progressive enhancement prioritizes basic content and functionality that works on all browsers and platforms. By starting with this baseline and then progressively adding more advanced features, developers can ensure that a website or web application is accessible to all users, regardless of their browser or device. This approach helps mitigate browser differences' impact on the user experience. The basic content and functionality remain intact, even if a specific browser does not support some features. This involves three key principles: Baseline functionality, Layering enhancement, and Feature detection.

Benefits of Progressive enhancement include Improved accessibility, Inclusive user experience, and future-proofing.

### Graceful degradation 
This involves designing web pages and applications with advanced features while providing fallbacks for browsers that don't support these features. For example, if a browser doesn't support [CSS gradients](https://developer.mozilla.org/en-US/docs/Web/CSS/gradient), a developer can provide a fallback image to ensure that the visual presentation is still consistent. This allows developers to provide a richer experience for users on more modern browsers without compromising the user experience on less capable devices or browsers. The key aspects of graceful degradation are Advanced feature implementation, Fallback solutions, Testing, and Quality assurance.

Benefits of Graceful degradation include Consistent functionality, Enhanced user experience, and Minimized user frustration.

### Use of modern web standards and technologies
As the web evolves, ensuring cross-browser compatibility becomes increasingly important to provide an optimal user experience. Developers should follow best practices and leverage modern web standards and technologies to accomplish this. For instance, [HTML5](https://developer.mozilla.org/en-US/docs/Glossary/HTML5) and CSS3 offer standardized specifications for creating dynamic and interactive web content. In addition, JavaScript frameworks like [React](https://developer.mozilla.org/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/React_getting_started) and [Vue.js](https://developer.mozilla.org/en-US/docs/Learn/Tools_and_testing/Client-side_JavaScript_frameworks/Vue_getting_started) provide powerful tools for building feature-rich websites and web apps. Developers can build a future-proof web experience using these standards and technologies.

Benefits include Improved performance, Enhanced security, Accessibility compliance, and Responsive Design.

### Testing on popular and relevant browsers

One of the most important best practices for cross-browser compatibility is thorough testing across relevant browsers. Given the various browsers and their different versions, it's important to test websites and web apps on a wide range of platforms. This helps identify browser-specific issues like broken rendering, layout misalignment, and bugs that affect functionality. Testing aims to ensure that users have a consistent experience, regardless of the browser they're using. Testing also helps ensure accessibility for users with disabilities or limited hardware capabilities.
   
## Techniques for Testing Cross-Browser Compatibility
Let's have a look at some techniques for Testing Cross-Browser Compatibility:

### Manual testing on different browsers and versions:
Testing websites and web applications on different browsers and versions can be done manually or with automated tools. Manual testing requires visiting the website on various browsers and platforms, while automated tools can simulate the browsing experience on different browsers. While manual testing is more time-consuming, it can uncover more nuanced issues that automated testing may miss. By testing manually and automating when possible, developers can more effectively catch cross-browser compatibility issues and ensure a consistent user experience.
Steps involved in manual testing:

- Identifying the browsers and operating systems that you need to test on. This will solely depend on the target audience for your website or web application.
- Installing the browser and operating system on your computer device.
- Developing a test plan that outlines the specific tests that you have to perform.
- Manually testing your website or web application on each installed browser and operating system.
- Documenting all compatibility issues that you may find.
- Fixing compatibility issues and repeating the testing process.


### Browser testing tools and online services:
Browser testing tools and services enable developers to automate cross-browser compatibility testing without installing different browsers and operating systems on their own computers. With these tools, developers can test their websites or web apps in a simulated browser environment that mimics the user experience on different platforms. Popular tools include [BrowserStack](https://www.browserstack.com/), [Sauce Labs](https://saucelabs.com/), and LambdaTest. These tools can save time and resources while still providing comprehensive testing.
   The process of testing web applications or websites using Browser testing tools and online services is quite the easy one. It entails:

- Signing up for the service and creating an account.
- Uploading your website or web application to the service.
- Selecting the browsers and operating systems that you want to test on.
- Running the tests.
- Reviewing the results and fixing any compatibility issues that you may find.



### Virtual machines and browser emulators:
Virtual machines (VMs) and browser emulators are powerful tools that can be used to test cross-browser compatibility. VMs allow you to run multiple operating systems on one computer, so you can test your website or web app on multiple browsers and systems. Browser emulators mimic the behavior of different browsers without the need to install them. Both types of tools offer advantages in terms of cost, time, and convenience, making them valuable for cross-browser testing.
   Steps involved in using VMs and browser emulators for testing cross-browser compatibility:

- Install a VM software on your computer.
- Download the operating systems and browsers that you want to test on.
- Create a VM for each operating system and browser.
- Install the browsers on the VMs.
- Test your website or web application on each VM.
- Document any compatibility issues that you may find.
- Fix compatibility issues and repeat the testing process.


## JavaScript Compatibility

JavaScript compatibility is the ability of JavaScript code to function correctly across different web browsers and their versions. As one of the most popular scripting languages, JavaScript is used in many websites and web applications to create interactive and dynamic experiences. Since there are many different browsers available, testing JavaScript code for compatibility is crucial to ensure a consistent user experience. This testing helps developers identify and fix any compatibility issues before the code goes live.


### Feature detection instead of browser detection: 
Feature detection is a technique used to check for the availability of specific JavaScript features in a browser. This technique is preferred over browser detection because it focuses on what a browser can do rather than guessing its capabilities based on its user agent string. By checking for the availability of features directly, developers can be sure that their code will function properly across a wider range of browsers, even those that may be using a spoofed user agent string. Feature detection helps to avoid compatibility issues and ensure a consistent user experience.

Some benefits of feature detection include Granular control, Simplified codebase, Improved performance, and Future-proofing.

### Utilizing polyfills and shims: 
A polyfill is a JavaScript library that emulates or replicates functionality that is not supported by a particular browser. This allows developers to use modern features and APIs without having to worry about whether a specific browser supports them. [Polyfills](https://developer.mozilla.org/en-US/docs/Glossary/Polyfill) bridge the gap between older browsers and modern standards, making it easier for developers to create cross-browser-compatible code. By providing an emulation layer, polyfills enable developers to use the latest language features without sacrificing compatibility.

[Shims](https://developer.mozilla.org/en-US/docs/Glossary/Shim) are similar to polyfills in that they provide functionality for unsupported features, but they differ in their purpose and scope. Shims focus on standardizing the APIs of various browser implementations, while polyfills aim to replicate missing functionality. With shims, developers can write code that will work consistently across browsers, regardless of whether the browsers support the underlying functionality. Shims are, therefore, more suited to situations where consistency is more important than complete emulation.

Polyfills and shims are powerful tools for achieving cross-browser JavaScript compatibility, especially for older browsers. They allow developers to take advantage of the latest language features and APIs, even when the browser doesn't natively support them. This is beneficial because it provides a consistent experience for users across different browsers and versions. In this way, polyfills and shims increase the compatibility and efficiency of websites and web applications, making them more accessible and user-friendly. They are beneficial in Feature parity, Progressive enhancement, Code reusability, and Future-proofing.

### Handling asynchronous operations consistently

Asynchronous operations, which are frequently used in modern web applications, present a unique challenge for achieving JavaScript compatibility. This is because different browsers may handle asynchronous operations in slightly different ways. These variations can lead to inconsistent behavior and errors that can affect the user experience. To mitigate this issue, developers must carefully consider how asynchronous operations are implemented and tested to ensure that the application functions correctly across all supported browsers.

Consistent handling of asynchronous operations is a crucial factor in delivering a reliable and consistent user experience across different browsers and versions. With careful planning, best practices, modern APIs, and robust testing, developers can ensure that asynchronous operations execute correctly in all supported browsers, regardless of their underlying features and capabilities. In turn, this helps to achieve cross-browser compatibility and improve the overall quality of the user experience.

## Cross-Browser Compatibility Tools

### BrowserStack, CrossBrowserTesting, Sauce Labs:
[BrowserStack](https://www.browserstack.com/) is a popular cross-browser testing platform that provides access to real browsers running on real devices. With BrowserStack, developers can test their websites and web applications on a wide range of browser and device combinations, including iOS and Android devices. The platform offers interactive testing, automated testing, and screenshot comparisons to identify visual inconsistencies across browsers. By using BrowserStack, developers can ensure that their code works consistently across all supported browsers and devices.

[CrossBrowserTesting](https://smartbear.com/product/bitbar/) is a popular cloud-based testing platform that provides access to real browsers and mobile devices for cross-browser testing. The platform offers both manual and automated testing, as well as visual testing for responsive design. It's a useful tool for developers who need to ensure that their websites and web applications function correctly and look consistent across different browsers and devices. CrossBrowserTesting also provides developer tools and plugins for popular IDEs and build tools.

[Sauce Labs](https://saucelabs.com/) is a cloud-based testing platform that supports testing on real browsers, virtual machines, and emulators. Developers can test their websites and web applications on a variety of environments, including mobile devices, desktop browsers, and operating systems. The platform supports both manual and automated testing, making it a versatile tool for testing the cross-browser compatibility of web applications.

### Browser developer tools for debugging
Google Chrome DevTools is a powerful set of developer tools that are integrated into the Google Chrome browser. These tools are designed to help developers inspect, debug, and optimize web applications. They offer a wealth of features for analyzing performance, monitoring network activity, debugging code, and more. Google Chrome DevTools can be accessed by pressing F12 or by navigating to the Chrome menu and selecting "More Tools" > "Developer Tools.
   
Mozilla Firefox Developer Tools offer similar features to Chrome DevTools, and they're built into the Mozilla Firefox browser. They include debugging and profiling capabilities, as well as tools for analyzing and optimizing performance and memory usage. Like Chrome DevTools, Firefox Developer Tools can be accessed by pressing F12 or through the Firefox menu. They're a convenient and useful resource for web developers who use Firefox.
   
Microsoft Edge DevTools are comparable to the developer tools offered by Chrome and Firefox. They offer the same type of features, such as debugging, profiling, and performance analysis. Like Chrome and Firefox, Microsoft Edge DevTools can be accessed by pressing F12 or through the browser's menu. These tools are a valuable asset for developers who work with the Microsoft Edge browser."
   
Safari Web Inspector is the built-in developer toolset provided by Apple's Safari browser. It offers a set of features for debugging and optimizing websites and web applications. The Web Inspector can be accessed by pressing Command + Option + I or through the Develop menu in Safari. The Safari Web Inspector is a convenient and powerful resource for developers who work with the Safari browser.
   
### Online validators for HTML, CSS, and JavaScript
Online code validators are an important resource for web developers, as they help identify and fix errors in HTML, CSS, and JavaScript code. By running your code through these validators, you can find errors and inconsistencies that might otherwise be overlooked. These tools are particularly useful for catching and fixing errors early in the web development process when they're easier to fix. They can also help improve the quality of your code and ensure that it adheres to best practices and standards.
   
- HTML Validators include: [W3C Markup validation service](https://validator.w3.org/), [HTML5 Validator](http://html5.validator.nu).
   
- CSS Validators include: [W3C CSS Validation Service](https://jigsaw.w3.org/css-validator/), [CSSLint](http://csslint.net/).

- JavaScript Validators include: [JSHint](https://jshint.com/), [ESLint](https://eslint.org/).


## Conclusion

To create websites and web applications that work consistently across a wide range of browsers and devices, developers must understand how HTML, CSS, and JavaScript are interpreted and implemented in different browser environments. They also need to make use of browser developer tools, code validators, and other resources to test and debug their code. This process may be complex, but it's essential to ensure that the web works as intended for everyone.