How To Debug React Apps Like A Senior Developer

Introduction

In this tutorial, we will explore effective debugging techniques for React applications, including Next.js, using tools that senior developers rely on. By the end of this guide, you'll be equipped with practical tips and tools to debug your React apps more efficiently.

Chapter 1: Install Dev Tools

Steps to Install React Developer Tools

• Search for "React Developer Tools" in your browser.
• Install the extension directly for supported browsers (e.g., Chrome, Firefox).
• For unsupported browsers, follow the installation instructions provided in the documentation on the official React site.

Benefits of React Developer Tools

• After installation, you will notice two new tabs in your browser’s developer tools: Components and Profiler.
• These tools provide valuable insights into your React project, enhancing debugging capabilities.

Practical Tip

• In Strict Mode, console logs may appear twice. To hide these duplicate logs:
  • Click the cog icon in the React Developer Tools.
  • Enable the Hide logs during second render option.

Chapter 2: Debugger Tips and Setup

Connecting VS Code to Your Browser

• Open the Debug panel in VS Code and select “web app (Chrome)”.
• Modify the configuration file (launch.json) to include your application's URL.
• Save the configuration.

Using Debugger Statements

• Insert debugger; statements in your code where you want to pause execution.
• This allows you to inspect variable values and application state at that point in time.

Using Breakpoints

• Click on the line number in VS Code to set a breakpoint.
• For React applications in Strict Mode:
  • Use hit counts to manage breakpoints. For example, to hit a breakpoint every second render, set the hit count to 2 (using the % operator).

Chapter 3: Next.js Debugger Setup

Setting Up Debugging for Next.js

• Create a launch.json file in your .vscode folder.
• Use the configuration provided in the Next.js documentation which includes:
  • Server-side debugging
  • Client-side debugging
  • Full-stack debugging

Debugging Behavior in Next.js

• Select the desired debugging mode (server, client, or full-stack) from the dropdown in the Debug panel.
• Set breakpoints and use the debugger as you would in a standard React application.

Chapter 4: Components Tab Features

Exploring the Components Tab

• The Components tab displays a hierarchical view of your application’s components.
• You can inspect props and state for each component.

Practical Tips

• Use the magic icon to label hooks with their variable names for easier navigation.
• You can manually change state values directly in the Components tab to see how it affects the UI.

Selecting Elements

• Use the selection tool to click on any element in your application. This will highlight the corresponding React component in the Components tab.

Chapter 5: Profiler Tab Features

Using the Profiler Tab

• Click the Start Profiling button to track component render times.
• Interact with your application, then click Stop Profiling to analyze render performance.

Analyzing Render Performance

• View the timeline of component renders and their respective durations.
• Identify components that take longer to render and optimize them accordingly.

Settings in the Profiler Tab

• Enable Record why each component rendered for detailed insights on re-renders.
• Use Throttle settings to simulate lower performance and test application behavior on less powerful devices.

Conclusion

In this tutorial, we covered essential debugging techniques for React and Next.js applications using developer tools. By installing React Developer Tools, connecting your code editor to the browser, and utilizing the Components and Profiler tabs, you can significantly enhance your debugging workflow. Explore these tools and tips further to improve your efficiency in resolving bugs and optimizing performance in your React projects.