Developers, You Can’t Escape the “Artistic Charm” of Full-Stack Debugging

Full-stack development is often likened to a complex balancing act, where developers need to juggle multiple responsibilities, such as front-end, back-end, database, etc. As the definition of full-stack development continues to evolve, debugging methods are also evolving. Full-stack debugging is a necessary skill for developers, but because it involves tracking down issues through multiple layers of an application, it often hits a personal blind spot . In this article, my goal is to explore the nuances of full-stack debugging and provide practical tips and insights for developers navigating the complex web of modern software development.

Please note that this is an introductory article that focuses primarily on front-end debugging aspects. In subsequent articles, I will delve deeper into other aspects of full-site debugging .

Full-stack development: a changing definition

The definition of full-stack development is as varied as the technology stack itself. Traditionally, a full-stack developer was defined as someone who can work on both the front-end and back-end of an application. However, as the industry has evolved, this definition has expanded to include operations (OPS) and configuration aspects. Modern full-stack developers are given higher expectations, and the pull requests they submit are best able to cover all the parts needed to implement a feature - back-end, database, front-end, and configuration. This requires them to be able to navigate freely between areas under the guidance of domain experts .

Full stack debugging approach

Just as full-stack development involves working across different areas, full-stack debugging requires a similar approach. The symptoms of a bug may appear on the front-end, but the root cause may be buried deep in the back-end or database layer. Full-stack debugging is all about tracking these issues through the layers and isolating them as quickly as possible. This is not an easy task, especially when dealing with complex systems where multiple layers interact in many ways . The key to successful full-stack debugging is understanding how to track issues through each layer of the stack and identifying common pitfalls that developers may encounter.

Front-end debugging: tools and techniques

Not “Just Console.log”

Front-end developers are often characterized as relying solely on Console.log for debugging. While this approach is simple and effective for basic debugging tasks, it falls short when . The complexity of front-end code has increased significantly, making advanced debugging tools a necessity . However, despite the many powerful debugging tools on the market , some developers still shy away from them and cling to old habits.

The power of developer tools

Modern web browsers come with powerful developer tools that provide extensive capabilities for debugging front-end issues. Available in browsers like Chrome and Firefox, these tools allow developers to inspect elements, view and edit HTML and CSS, monitor network activity, and more. One of the most powerful, yet underutilized, features of these tools is the JavaScript debugger.

The debugger allows developers to set breakpoints, step through code, and inspect the state of variables at different points in the execution process. However, the complexity of front-end code, especially when it is obfuscated for performance reasons, can make debugging a challenging task.

We can launch the browser tools on Firefox using the following menu:

On Chrome, we can use this option:

Personally , I prefer using Firefox because their developer tools are more convenient, but both browsers have similar features. Both have great debuggers (as you can see in the Firefox debugger below); unfortunately, many developers don't invest the effort to explore this powerful tool.

Dealing with code obfuscation

Code obfuscation is a common practice in front-end development to protect proprietary code and reduce file size for better performance. However, obfuscation also makes the code difficult to read and debug. Fortunately, both Chrome and Firefox development tools provide the ability to deobfuscate code, making it easier to read and debug. By clicking the curly brace button in the toolbar, developers can convert a line of obfuscated code into a well-formatted, debuggable file.

Another important tool in the fight against obfuscation is source maps. Source maps are files that map obfuscated code back to its original source code (including comments). When generated and configured correctly, source maps allow developers to debug the original code instead of the obfuscated version. In Chrome, this feature can be enabled by ensuring that " Enable JavaScript source maps" is checked in the Developer Tools settings .

You can use the following code in your JavaScript file to point to the sourcemap file:

1. //@sourceMappingURL=myfile.js.map

To get this to work in Chrome , we need to make sure that " Enable JavaScript source maps " is checked in the settings . While it's sometimes turned on by default, it never hurts to verify:

Cross-layer debugging

Isolating issues across the stack

In full-stack development, problems often arise in one layer but have their root cause in another. For example, a front-end error might be caused by a misconfigured back-end service or a database query that returns unexpected results. Isolating the root cause of these problems requires a methodical approach, starting with the symptoms and working backwards layer by layer.

A common strategy is to simulate the problem in a controlled environment, such as a local development setup, where each layer of the stack can be tested in isolation. This helps narrow down the potential source of the problem. Once the problem is isolated to a specific layer, developers can use the appropriate tools and techniques to diagnose and resolve the problem.

The Importance of System-Level Debugging

Full-stack debugging is not limited to application code. Often, problems are caused by the surrounding environment, such as network configuration, third-party services, or hardware limitations. For example, a few years ago we had an issue where WebSocket connections were frequently disconnected , affecting production . After extensive debugging, we found that the issue was caused by the CDN provider (CloudFlare) - an issue that could only be identified by debugging the entire system, not just the application code.

System-level debugging requires a broad understanding of how different components of the infrastructure interact with each other. It also involves using tools that can monitor and analyze the behavior of the entire system, such as network analyzers, logging frameworks, and performance monitoring tools.

Embrace complexity

Full-stack debugging is inherently complex because it requires developers to navigate multiple layers of an application, often dealing with unfamiliar technologies and tools. However, this complexity also provides opportunities for growth. By taking on the challenge of full-stack debugging, developers can expand their knowledge and become more versatile in their role .

One of the key benefits of full-stack development is the ability to collaborate with domain experts. When debugging issues that span multiple layers, it’s important to leverage the expertise of colleagues who specialize in a specific area. This collaborative approach not only helps solve problems more efficiently, but it also fosters a culture of knowledge sharing and continuous learning within the team.

As tooling continues to evolve, so too do the tools and techniques available for debugging. Developers should strive to stay up to date with the latest advances in debugging tools and best practices. Whether it's learning to use new features in browser development tools or mastering system-level debugging techniques, continuous learning is essential to success in full-stack development.

Conclusion

Full-stack debugging is a critical skill for modern developers, and we mistakenly believe that it requires a deep understanding of both the application and its surrounding environment. In fact, by mastering the tools and techniques discussed in this/follow-up articles, developers can more effectively diagnose and resolve issues that span multiple layers of the stack. Whether you are dealing with obfuscated front-end code, misconfigured back-end services, or system-level issues, the key to successful debugging lies in a methodical and collaborative approach.

You don't need to understand every part of the system, you just need to be able to eliminate the impossible.

Original title: The Art of Full Stack Debugging , author: Shai Almog