JavaScript is an essential language in web development. However, encountering errors during development is unavoidable. In this article, we introduce effective debugging methods for beginners, techniques for finding bugs, and efficient development practices.

Contents
  1. Debugging Basics
  2. How to Find Bugs
  3. Recommended Tools and Resources
  4. Conclusion

Debugging Basics

Debugging is a fundamental part of programming. To identify and resolve errors, it is important to follow the steps below.

Using Console Logs

Use console.log() to check variables and calculation results. This helps you understand which part of the program is not functioning as expected.

Setting Breakpoints

Use the browser’s developer tools to set breakpoints on specific lines of code. This pauses the program execution when that line is reached, allowing you to inspect the state of variables.
Breakpoints are a core element of debugging, used to stop a program at a specific point and investigate its state at that moment. Below is an explanation of how to set breakpoints.

Specific Steps for Setting Breakpoints

  1. Selecting the Appropriate Breakpoint:
    Identify the part of the code where the issue is likely occurring or where you want to verify behavior. Typically, lines where variable values change or where functions are called are suitable.
  2. Setting the Breakpoint:
    Use development tools (e.g., Google Chrome Developer Tools, Visual Studio Code, etc.) to set a breakpoint on the identified line. This can usually be done by clicking to the left of the corresponding line number. The line number will be highlighted, often with a red dot or icon, indicating that the breakpoint has been set.
  3. Running the Program:
    Run the program as usual. The program will automatically pause when it reaches the line with the breakpoint.
  4. Checking the State:
    When the program pauses, you can inspect the current variable values, the execution stack, and objects within the scope. This information helps identify the cause of the error.
  5. Stepping Through the Code:
    Many development tools allow you to step over to the next line (step over), dive into functions (step in), or exit from functions (step out). This enables you to closely follow the execution flow of the code.
  6. Identifying and Fixing the Issue:
    After identifying the root cause using breakpoints and step execution, modify the code and run it again to confirm that the issue has been resolved.

　
By utilizing breakpoints, you can accurately understand what is happening in specific parts of your code and effectively identify the cause of errors. Beginners can improve their debugging skills by repeating this process.

How to Find Bugs

The best way to find bugs is to carefully read and understand your code. Pay attention to the following points:

  • Recognizing Code Patterns:
    Be aware of common error patterns (such as undefined variables, typos, or missing closing brackets).
  • Code Reviews and Pair Programming:
    Reviewing code with others can provide new perspectives and help uncover errors you may have overlooked.

Recommended Tools and Resources

How to Debug Using Google Chrome Developer Tools

An ideal tool for debugging JavaScript. It allows you to set breakpoints, monitor variables, and analyze performance.

Steps and Explanation

  1. Open the Code in Your Browser:
    Open the web page where JavaScript is running in Chrome.
  2. Launch Developer Tools:
    Right-click and select “Inspect,” or press Ctrl+Shift+I (Windows) or Cmd+Opt+I (Mac).
  3. Go to the Sources Tab:
    Select the “Sources” tab from the top of the screen.
  4. Set a Breakpoint:
    Find the source code and click to the left of the line number where you want to set a breakpoint. When execution reaches this line, it will pause.
  5. Run and Monitor the Code:
    Interact with the web page to execute the code up to the set breakpoint. When paused, you can inspect variable values and the state of the stack.

Detailed Information and Resources

For more details about Google Chrome Developer Tools, visit the official Google Developers website.

How to Debug Using Visual Studio Code

A highly popular code editor equipped with powerful debugging features and extensions.

Steps and Explanation

  1. Open Your Project in Visual Studio Code:
    Launch VS Code and open the project you want to debug.
  2. Go to the Debug View:
    Click the debug icon (the bug-shaped icon) in the sidebar.
  3. Configure the launch.json File:
    Click “Add Configuration” and select the debugging settings that match your programming language. This will add a launch.json file to your project.
  4. Set a Breakpoint:
    Place the cursor on the line you want to debug and click the left margin to set a breakpoint.
  5. Start Debugging:
    Click the green play button to begin debugging. When the code stops at a breakpoint, you can inspect variable values and the call stack.

Detailed Information and Resources

More details about Visual Studio Code’s debugging features are available on the official Visual Studio Code website.

Conclusion

Errors are unavoidable in JavaScript development, but by learning effective debugging techniques, you can overcome these obstacles and become a stronger developer. We hope this guide helps improve your development skills.

　
*Please use this information at your own discretion.*

Breakpoints debug Error handling