Mastering TypeScript Debugging with Visual Studio Code: Common Mistakes and How to Fix Them



April 25, 2023


April 25, 2023

Debugging TypeScript can be a challenge but it's a crucial part of app development as it helps developers identify and fix errors in their code. While working with TypeScript, developers may face common problems like type mismatches, syntax errors, and runtime exceptions.

Visual Studio Code provides several tools to help developers debug TypeScript code efficiently. Through this blog, we will explore how to use these tools to troubleshoot and resolve issues effectively.

Stay tuned to learn how to master TypeScript debugging with Visual Studio Code! And by the end of this blog, you will have a better understanding of how to tackle any debugging issues that may arise in your TypeScript projects with ease. 

So let's dive in! 

Common Mistakes in Debugging TypeScript 

Debugging TypeScriptcan code can be quite a daunting task even for the most seasoned developers. So, let's take a look at common mistakes we made while debugging TypeScript code.

1. Incorrect Breakpoints:

 One common mistake is setting breakpoints on the wrong line of code or not setting them at all. Make sure that the breakpoints are set on the correct line of code and that they are being hit when the code is executed.

2. Not Compiling TypeScript Code:

 TypeScript is a compiled language, and the code needs to be compiled before it can be executed. Make sure that the code is compiled correctly. So that any changes made are compiled before debugging.

3. Source Maps Not Generated: 

Make sure that source maps are generated correctly, as they are required to map the compiled JavaScript code back to the TypeScript source code during debugging.

4. Incorrect Launch Configuration: 

Another common mistake is setting the incorrect launch configuration for debugging. Make sure that the launch configuration is set up correctly and that it points to the correct entry point of the application.

5. Not Using the TypeScript Debugger: 

VS Code has a built-in TypeScript debugger that allows developers to debug their TypeScript code easily. Make sure that you are using this debugger and not the standard JavaScript debugger.

6. Incorrectly Typed Variables: 

TypeScript is a statically typed language, and incorrect typing of variables can cause debugging errors. Make sure that variables are typed correctly, and “any” type casting is done correctly.

7. Not Using Debug Console: 

VS Code has a debug console that allows developers to view the values of variables and debug information during runtime. Make sure that you are using this console to debug your TypeScript code.

8. Choosing the Wrong Debugging Options in VS Code

 Another common mistake is not using the right debugging options in VS Code. For example, if you're debugging client-side code, you'll need to use different options than if you're debugging server-side code.

9. Not Enabling Strict Mode

Enabling strict mode in TypeScript is essential for catching potential errors during development and debugging. To enable strict mode in TypeScript, set the "strict" flag to true in the tsconfig.json file. 

 Some of these errors include- 

  1. Using undeclared variables or passing the wrong number of arguments to a function are caught during development. 
  2.  Without strict mode, TypeScript may allow type mismatches between variables, which can cause errors during runtime. 
  3.  It also ensures that all code is necessary and used, which helps to reduce potential errors and bugs during runtime.
  4. Strict mode ensures that TypeScript code can interoperate smoothly with JavaScript code.

10. Redeclaring Interfaces

It can lead to unexpected behavior when your code is compiled and executed because TypeScript will treat the two interfaces as separate, unrelated types. To fix this issue, you should only declare each interface once in your codebase and use the extends keyword to add new properties to an existing interface.

Moreover, understanding how TypeScript compiles to JavaScript is also essential for effective debugging. It's common to see developers struggle with this aspect of TypeScript when they first start using the language. 

By avoiding these common mistakes and understanding the intricacies of TypeScript debugging, you'll be able to streamline your development process and become a more efficient programmer.

Troubleshooting TypeScript Debugging issues in VS Code

Debugging TypeScript code in VS Code can be tricky, but there are several tools and techniques that can help streamline the process. 

1. Troubleshooting Breakpoints and Source Maps

Breakpoints and source maps are essential tools for debugging TypeScript code in VS Code. Breakpoints allow you to pause the execution of your code at specific points and inspect variables, while source maps link TypeScript code to the generated JavaScript code, making it easier to debug. However, even with these powerful tools, issues can still arise.

To troubleshoot these problems, make sure that your breakpoints are set correctly and in the right place in your code. Additionally, check if source maps are properly configured and enabled in your project settings. If you're still having trouble, try clearing the cache or restarting VS Code. 

2. Following Best Practices to Avoid Common Issues

To effectively debug TypeScript code in Visual Studio Code, it is essential to follow best practices and avoid common issues. One way to ensure a smooth debugging experience is to set up the debugger correctly and use console.log statements to troubleshoot and understand where your code is failing. 

Additionally, it is important to make sure that you are using the latest version of VS Code and the TypeScript extension. Setting breakpoints at key points in your code can help pause execution and inspect variables, while also checking for common issues like incorrect file paths, syntax errors, or version mismatches.

Configuring VS Code for TypeScript Debugging

To effectively debug TypeScript in VS Code, you need to first configure your environment. This involves installing the TypeScript compiler and VS Code debugger extension, as well as setting up launch.json to specify how to launch and debug your TypeScript code.

1. Install Debugger

Install the Debugger for Chrome extension in VS Code.

2. Create launch.json file

Next, create a launch.json file in your project's .vscode folder. You can do this by opening the Command Palette (Ctrl/Cmd + Shift + P) and selecting "Debug: Open launch.json". Select "Chrome" as the debug environment. Add the following configuration to the launch.json file:

3. Set Breakpoints

Set breakpoints in your TypeScript code by clicking on the gutter next to the line number or by pressing F9.

4. Start Debugging

Start your project in debug mode by clicking the "Start Debugging" button in VS Code's Debug panel or by pressing F5. Your application will launch in a Chrome browser window. Interact with your application to hit your breakpoints and inspect your code.

These steps will allow you to set up a basic debugging configuration for your TypeScript application in VS Code. You can modify the launch.json file to fit your specific needs, such as setting environment variables or using a different debug environment.

Note: Here we have assumed that the tsconfig.json file is properly configured for TypeScript compilation before starting the debugging process. It is important, especially for more complex projects. This can ensure that your code is compiled correctly and that any TypeScript compilation errors are resolved before you begin debugging your code.

Advanced Techniques for TypeScript Debugging

Advanced techniques for TypeScript debugging can help you identify and fix complex issues more efficiently.

1. Debugging Client-Side Script

Debugging client-side scripts in TypeScript can be challenging, particularly when dealing with asynchronous JavaScript. Fortunately, Visual Studio Code provides debugging tools that can help you identify and fix issues in your code. 

By using breakpoints, watches, and console.log statements to debug your code and inspect variables at runtime, you can quickly resolve any issues. Additionally, the debugger can be used to step through the code line by line and visualize the call stack, allowing you to better understand how your code flows and identify any errors or issues. 

2. Debugging Server-Side Script

To effectively debug server-side scripts, it's important to have a clear understanding of the code structure, variables, and functions involved. You can use breakpoints and watch expressions to identify errors and bugs in your code, as well as console.log statements to track the flow of your program. 

3. Generating Source Maps for Debugging

Generating source maps can help streamline the debugging process and enable developers to debug TypeScript code directly in browsers or in debugging tools like VS Code.

Source maps act as a link between the TypeScript code and the generated JavaScript code, allowing developers to identify errors and bugs quickly. To use source maps for debugging, developers need to set the "sourceMap" flag to true in the TypeScript compiler options. 

Additionally, source maps can be configured to exclude certain files or directories for faster build times. By generating and using source maps effectively, developers can simplify the process of debugging TypeScript code and improve their productivity.


Visual Studio Code provides several tools to help you debug your TypeScript code effectively. With these tools at your disposal, you can ensure that your TypeScript code is always running smoothly. 

In the blog, we have discussed the common mistakes made while debugging TypeScript code and how to troubleshoot those issues in the VS Code. Also, we have covered advanced techniques for debugging TypeScript code and how to debug client-side and server-side scripts. 

With the configuration and debugging techniques we have discussed, you can build robust TypeScript apps with ease. 

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