React Native Debugging : Beginners Guide

React Native is a game changer in mobile app development as it allows us to build cross platform apps using React framework. This is great because we don’t need a separate code base or development skills for iOS and Android. While this works on React framework it's not as easy to debug the issues. In any conventional web app we can just open our browser’s dev tools and we will get all the tools needed to debug. We get the UI inspector, source tab for putting debuggers, and network tab for debugging network calls. But for React Native apps it's not as straightforward. Before delving into the tools and techniques, let's understand why React Native debugging is so vital. 

Why React Native debugging matters

Impact on app reliability and user experience

Debugging React Native apps, or any app for that matter can help fix issues and bugs before they manifest as App crashes, logical failures, network issues or other code errors. By resolving those issues during development you can provide a more stable release. Effective react native debugging includes implementing error handling and exception management. This ensures that when unexpected issues do occur, the app can gracefully handle them, preventing complete application failures. Debugging can also help discover performance issues that the users might face. Solving these issues will give your users a smooth experience which is vital for keeping users engaged. Solving issues before they reach the customers, and giving them a smooth user experience, goes a long way in building trust for your product. Debugging issues in the production environment is also a key to customer satisfaction and revenue, hence the need for react native debugging in both development and live environments. 

Benefits for developers and businesses

Effective React Native debugging is a fundamental skill for react native mobile developers. Exposure to different types of issues helps developers become more proficient in problem solving and code analysis. Using efficient, good debugging tools and practices can increase productivity of developers significantly and eventually lead to time and cost saving for the business. As mentioned above providing a good error free experience for users can help in building trust in your product or brand and keep your customer loyalty intact. 

React Native debugging techniques, strategies and tools

To debug react native apps, there are techniques and tools that react native developers would find handy. Some of these are listed here but we discuss some of the key techniques below while using some of these tools. 

Setting breakpoints

Adding breakpoints to your code while debugging is a great way to search for issues. Breakpoints help us understand the code flow and the state of variables at a particular point of code execution. It’s also a great way to understand any new codebase. Adding breakpoints to your React Native app is not as straightforward as something you can do in any web app. But there are some tools that solve this problem.

Chrome dev tools

You can run your app in debug mode and then enable remote debugging. This opens a new Chrome tab. In the newly opened tab, open the developer tools and navigate to sources tab. In there you will see all your project files and folders just like you will see for a normal web app. Navigate to the desired file and add a breakpoint to the required line. This is a fundamental aspect of React Native debugging. 

VS Code

VS Code is the most widely used IDE for React Native debugging and development. Having your debugging tool in the IDE can speed up your development process. For React Native debugging, you need to have the React-Native-Tools extension installed. If you have the extension installed just add a breakpoint next to the line number. After making necessary changes to the “launch.json” file, run your app through “run and debug” and it will start pausing your app on the breakpoints. 

React Native debugger

React Native debugger is a popular standalone debugging tool that provides a user-friendly interface for React Native debugging. It integrates with the Chrome Developer Tools and offers various features. You need to install “React Native Debugger” in your system for this to work. Then you need to start your app in development mode. After your app starts running, open React Native Debugger and connect your app from the list of running connections. In the sources tab of the debugger, you will see all your project files and folders just like you will see in Chrome dev tools. You can then add a breakpoint to the required line and start interacting with your app.

Stepping through code

After adding breakpoints through any of the above-mentioned methods in React Native debugging, your app will pause at your added breakpoint during the code execution. You can navigate the code line by line, jump inside function definition, and understand your code flows. This is a great method for understanding any issues or overall understanding of your program’s behavior in React Native debugging. After your app pauses on your breakpoint, you can do any of the following:

• Step over (F10): This allows you to move to the next line of code in React Native debugging. If the next line contains a function call, it will execute the function and pause at the next line.
• Step into (F11): If the next line of code is a function call, "Step Into" will take you inside the function to examine it line by line in the context of React Native debugging.
• Step out (Shift + F11): If you're inside a function and want to return to the calling function, use "Step Out" as part of your React Native debugging process.
• Continue execution (F8): When you've stepped through code and inspected what you needed in React Native debugging, you can continue the execution by clicking the "Play" button (F8) in DevTools.
  

Evaluating variables in React Native Debugging

Evaluating variables is a crucial part of React Native debugging, as it allows you to inspect the state of your application and understand how variables are changing during code execution. Once your app stops at the added breakpoint during React Native debugging, you can check the variable value by just hovering over it. You can also see the sequence in which that particular function is called during the code execution in the “Call Stack” panel. This works no matter which tool you use for React Native debugging.

Inspecting component hierarchy

Component Hierarchy in React Native is the tree-like organization of components. This is similar to a DOM structure that we see in inspect tab Chrome devtools.

You can inspect the UI component Hierarchy by using the “React Devtools”.” “React Devtools” is a Chrome extension used for debugging React apps. Same extension can be used for debugging React Native apps also. You just need to run your app in debug mode, enable remote debugging and when the Chrome tab opens. open the React devtools tab. You will see the whole Component Hierarchy.

Similarly, “React Native Debugger” also supports viewing component hierarchy. After connecting your app to “React Native Debugger”, you can view the component Hierarchy in the UI inspect panel. Inspecting component hierarchy doesn’t work in VS code.

After inspecting a particular element in the hierarchy you can also check the associated styles of the component. This helps in understanding the structure of your application and also debug any UI related issues.

Debugging state and props

Checking state and props are integral parts of any React Native debugging. It forms the basis of the data flow and the business logic of your application. Hence inspecting and evaluating state and props becomes important for a React Native developer.

As mentioned above “React Devtools” chrome extension is a great tool for debugging your application’s state and props. You can select any component from the component hierarchy and view its state and props. You can also monitor the change in state and props of the component by interacting with your app and seeing the changes in devtools.

“React Native Debugger” also works in the same ways for monitoring components state and props.

Monitoring your state and props while interacting with the app is a great way to solve bugs related to data flow in your application.

React Native debugging common issues

Debugging network and data issues

Tracking network calls during debugging and development is essential for monitoring API calls, identifying potential issues, and improving the overall performance of your application. In the debug menu of your phone or emulator which is running your React Native app, you can select “Toggle Inspector”. A UI with multiple tabs will open, and under the network tab you can view all the network requests as and when they are going in your app. Apart from this, other external tools also support tracking the network calls in React Native.

Zipy 

Zipy is a new entry in the field of react native debugging. Zipy helps to provide a complete picture of your production issues and helps you debug live customer bugs faster. From crash logs, to ANRs, network requests, ADB logs to custom exceptions, all can be detected and monitored by Zipy. Zipy SDK can be plugged into your react native app for faster debugging of customer problems. To learn more check here. 

React Native debugger

You need to connect your app to the React Native Debugger tool and then go to the “network” tab to view the network calls. This works if network inspection is enabled. You can enable network inspection by opening the context menu (by right-clicking on the left panel) and selecting “Enable Network Inspect”. You can filter requests by various criteria, including request type (e.g., XHR, Fetch), status code, method, and URL. You can Click on a specific request to inspect its details, including headers, request and response data, and timing information.

Reactotron

Reactotron is another popular tool for debugging React Native apps. It’s a great tool which offers many debugging features along with tracking Network requests. You need to install Reactotron and then run your app in debug mode. You can see your network requests in the API tabs in Reactotron. For more details on installation and how to use Reactotron refer this.

Performance and memory optimization

Optimizing performance of your app is an important part of the development process for any developer. Providing smooth and crash free user experience is crucial for any product. For Optimizing you need to understand how to monitor your app’s performance. You can do that with following tools

React devtools

React Devtools is a great tool if you want to analyze your app's re-renders. You need to enable remote debugging in your app for React Devtools to work as mentioned above. Once the browser opens, open the profiler tab in your Chrome devtools. Then start recording and perform actions on your app. After you stop recording it will show all the components and how many times it rerendered. You can identify unwanted rerenders and solve them.

React Native debugger

Similar to React Devtools, React Native Debugger also has a performance tab in which you get to see the components and their renders. Analyzing and optimizing performance is a continuous process. Performance issues in apps are not easily identified. So Profiling and optimizing should be an ongoing part of your development process.

Debugging Redux

State management in React Native apps becomes very crucial when the app size grows. There are a lot of tools out there for state management but Redux is the most popular state management library for React Native. Using a state management library like Redux helps a lot in managing your application’s data and state, but can lead to many issues. Debugging Redux becomes very important while debugging any issue in React Native.

Just like any React app, Redux devtools Chrome extensions also work with React Native. Just as you will use React Devtools to debug your state, props or component hierarchy, you can use Redux devtools. It will show all of your Redux state and also the diffs between them whenever any state change happens.

Other tools like Reactotron also support debugging Redux states.

To understand more about this you can check the top react native debugging tools listed here. 

Best practices for effective React Native debugging

• Debugging workflows and methodologies: Effective debugging is not just finding errors and bugs, but a necessary skill for any developer. You need to develop a systematic workflow and methodology. This might include steps like replicating the problem, examining error messages, setting breakpoints, and gradually narrowing down the source of the problem.
• Real-device vs. emulator testing: Testing your app on real devices as well as emulators is important. Both real devices and emulators can help debug or reproduce issues but both have their pros. Real devices can help find hardware specific issues such as app performance or usability issues, whereas emulator testing offers faster iteration and broader testing coverage.
• Version control integration: Version control plays a significant role in development and debugging. It allows you to track changes in your codebase and also which developer made those changes.

Handling React Native debugging in a production environment

Debugging doesn't end when you release your app to production, it's an ongoing process. Here's how to handle React Native debugging in a production environment

• Handling critical issues in production: Critical issues such as crashes can have a huge impact on overall user experience. So implementing robust error handling, logging and crash reporting mechanisms in the production build of your app becomes very important. Tools like Firebase help in monitoring crashes and exceptions with good UI.
• Crash reporting and debugging: Crash reporting services are invaluable for diagnosing and addressing crashes in production. They collect data on crashes, symbolicate stack traces, and provide you with insights into the root causes. You can then use this data to prioritize and fix issues efficiently.

To summarize, react native is quite popular amongst mobile app developers today. It is important to understand how to debug and solve react native code issues in various development phases including development, QA and production environments. Various techniques and react native debugging tools like chrome dev tools, VS Code extensions and react native debugger along with third party tools have been shared to throw some light on this topic. Zipy is one such product which helps in debugging and fixing live customer bugs in production environments. Check out this page to apply for access. 

React Native Debugging with Zipy

How to Integrate React Native SDK

• Integrating Zipy's React Native SDK is a crucial step in enhancing your app's debugging capabilities. Start by installing the SDK through your project's package manager. This is typically done via a simple command in your terminal. Once installed, the next step is to import the Zipy module in the main file of your application. This integration is crucial for enabling the SDK to monitor and capture data effectively.
• After importing, you'll need to configure the SDK. This involves setting it up with a unique token specific to your project, which you can find in your Zipy dashboard. This token is essential as it links your app with Zipy's services, ensuring secure and accurate data transmission.
• The final step is initializing the SDK. This should be done as early as possible in your app's lifecycle, ideally in the root component. Early initialization ensures that Zipy starts capturing data right from the app's launch, providing comprehensive insights from the get-go.

Data Captured by Zipy to Debug Customer Issues

Zipy's SDK is designed to capture a wide array of data, crucial for in-depth debugging:

• Error Logs and Exceptions: It automatically logs all uncaught exceptions and errors. This functionality is vital for identifying and understanding crashes and unexpected behaviors in your app.
• Network Requests and Responses: The SDK tracks all outgoing and incoming network activity. This includes detailed logs of API requests and responses, which are critical for diagnosing issues related to network communications and server interactions.
• User Sessions and Interactions: One of Zipy's key features is its ability to record complete user sessions. This includes tracking the user's navigation through screens and their interactions within the app. This data is invaluable for understanding the user journey and identifying points where users face issues.
• Performance Metrics: Zipy monitors essential performance metrics like response times, rendering speeds, and more. These metrics help pinpoint performance bottlenecks and device-specific issues, which are crucial for optimizing the app's performance across different devices.
• Custom Events and Logs: Besides automatic tracking, Zipy allows developers to log custom events and messages. This feature is particularly useful for monitoring specific actions or states within the app that are crucial for your unique debugging needs.

Conclusion

In the realm of React Native development, debugging stands as a pillar of success. Tools like Zipy not only simplify the debugging process but also bring a level of depth and insight into app performance and user experience that was previously hard to achieve. Effective debugging leads to higher-quality applications, elevates user satisfaction, and ultimately contributes to the success of the product. As developers embrace advanced debugging tools and strategies, the quality and reliability of React Native applications are set to reach new heights.