Resolving Debugging Problems with Blazor WASM with Visual Studio 2022: Third-Party JavaScript Libraries Resulting in Breakpoints

Why Debugging Blazor WASM Apps with Visual Studio 2022 and Chrome Can Be Frustrating

Debugging a Blazor WebAssembly (WASM) application can become frustrating when Visual Studio 2022 continuously breaks on exceptions from third-party JavaScript libraries. These libraries, like Stripe checkout or Google Maps, can throw errors, halting your progress. As a developer, you may find yourself clicking "Continue" repeatedly, which interrupts your workflow.

This problem becomes especially apparent when you switch to a new development machine. Even after importing old settings or reinstalling Visual Studio, the issue persists. Debugging third-party JavaScript becomes a hassle, making it difficult to focus on your Blazor WASM app itself.

Many developers experience the same challenge when dealing with dynamic JavaScript files, which Visual Studio seems to break on unnecessarily. Despite trying multiple settings combinations or toggling Chrome's breakpoints, the issue often remains unresolved, increasing frustration.

In this article, we'll explore some steps that could help minimize these interruptions. If you've encountered similar problems in Visual Studio 2022 when debugging with Chrome, these tips might save you from repeatedly clicking "Continue" and help you return to a smoother development experience.

Command	Example of use
window.onerror	This is an event handler in JavaScript that catches global errors in scripts. In the Blazor app example, it is used to intercept errors from third-party libraries (e.g., Stripe or Google Maps) and handle them without breaking the execution.
Pause on Caught Exceptions	A Chrome DevTools setting that determines whether to pause execution on exceptions that are already handled by the code. Disabling this option helps avoid unnecessary breaks on non-critical third-party library errors during debugging.
Exception Settings	In Visual Studio, this setting lets developers specify how different types of exceptions should be handled. For example, turning off "JavaScript Runtime Exceptions" helps stop Visual Studio from breaking on JavaScript errors from external libraries.
window.onerror return true	This return value in the error handler indicates that the error has been handled and should not be propagated further. It’s used to prevent the application from breaking on exceptions thrown by third-party libraries.
Assert.True()	A method from the xUnit testing framework that checks if a given condition is true. In the error handling test, it’s used to ensure that the custom error handling logic functions correctly by allowing the test to pass if the error is successfully caught and handled.
HandleError()	This is a custom function in the unit test used to simulate errors from third-party JavaScript libraries. It helps verify whether the error handling code works as expected in different scenarios.
Uncheck JavaScript Runtime Exceptions	In the Visual Studio Exception Settings panel, unchecking this option prevents the debugger from breaking on every JavaScript runtime exception, which is useful when exceptions from third-party libraries are causing disruptions during debugging.
Sources tab (Chrome DevTools)	This section of Chrome’s developer tools allows developers to inspect and control JavaScript execution. By managing breakpoints here, including disabling them for specific scripts, you can control where Chrome pauses during debugging.

Optimizing JavaScript Debugging in Blazor WASM with Visual Studio 2022

When developing a Blazor WebAssembly (WASM) app in Visual Studio 2022, it's common to encounter issues where the debugger repeatedly breaks on exceptions in third-party JavaScript libraries. This happens because Visual Studio is designed to catch exceptions during runtime, including those thrown by external scripts like Stripe checkout or Google Maps. To solve this, the scripts provided focus on controlling how Visual Studio and Chrome handle these exceptions. For example, disabling in Visual Studio prevents the debugger from pausing on non-critical errors, allowing you to focus on relevant debugging tasks.

The Chrome DevTools script also plays a vital role in this process. By tweaking the setting, you instruct Chrome to avoid breaking on errors that are already being handled within the JavaScript code. This is especially useful when working with dynamically loaded JavaScript files from third-party libraries, as these can often throw exceptions that do not impact your Blazor app directly. Disabling this option helps maintain a smooth debugging flow in the browser.

The custom handler adds another layer of error management directly within your application. By setting up this error handler, any errors thrown by specific libraries like Stripe or Google Maps are intercepted and logged rather than breaking the application. This ensures that the app continues running without interruption, which is crucial for maintaining a productive development environment. The script checks the source of the error and stops it from propagating if it originates from a third-party library.

Lastly, adding unit tests helps ensure that your error-handling mechanisms are functioning as expected. By writing tests that simulate JavaScript errors, you can validate that the application continues to run smoothly even when third-party scripts fail. These tests use frameworks like xUnit to verify that exceptions are properly caught and handled by your custom code. This approach not only improves the stability of your app but also reduces the number of disruptions caused by third-party JavaScript, leading to more efficient debugging in Visual Studio.

// Step 1: Open Visual Studio
// Step 2: Navigate to 'Debug' -> 'Windows' -> 'Exception Settings'
// Step 3: In the Exception Settings window, look for 'JavaScript Runtime Exceptions'
// Step 4: Uncheck the box next to 'JavaScript Runtime Exceptions'
// This will stop Visual Studio from breaking on JavaScript exceptions in third-party libraries
// Step 5: Restart debugging to apply the changes
// Now, Visual Studio will ignore JavaScript exceptions thrown by libraries like Stripe or Google Maps

// Step 1: Open Chrome DevTools (F12)
// Step 2: Go to the 'Sources' tab in DevTools
// Step 3: Click on the 'Pause on Exceptions' button (next to the breakpoint icon)
// Step 4: Make sure that 'Pause on Caught Exceptions' is disabled
// Step 5: This prevents Chrome from breaking on non-critical exceptions in dynamic scripts
// You can continue debugging without being interrupted by third-party JavaScript exceptions

// Step 1: Create a custom JavaScript error handler
window.onerror = function (message, source, lineno, colno, error) {
   console.log('Error caught: ', message);
   if (source.includes('Stripe') || source.includes('GoogleMaps')) {
       return true; // Prevents the error from halting execution
   }
   return false; // Allows other errors to propagate
}
// Step 2: Add this script to your Blazor app's index.html or _Host.cshtml file

// Step 1: Write a unit test for JavaScript error handling
using Xunit;
public class ErrorHandlingTests {
   [Fact]
   public void TestJavaScriptErrorHandling() {
       // Simulate an error from a third-party library
       var result = HandleError("StripeError");
       Assert.True(result); // Ensures the error is handled without breaking
   }
}

Managing Dynamic JavaScript Exceptions in Blazor WASM

When debugging a Blazor WebAssembly (WASM) app, one of the less discussed but crucial aspects is how Visual Studio handles dynamic JavaScript exceptions. These exceptions often stem from third-party libraries like Stripe or Google Maps, which may load scripts dynamically. Visual Studio treats these as "[dynamic]" JavaScript files and breaks execution when an error is thrown, even if the error doesn't directly affect your application. This can lead to multiple unnecessary interruptions during debugging, which disrupts your workflow and increases frustration.

To minimize these interruptions, it's important to configure your development environment correctly. Visual Studio provides several options for controlling breakpoints and exceptions. For example, turning off "Just My Code" or disabling JavaScript debugging can help prevent the IDE from catching errors that are irrelevant to your project. However, these solutions may not be foolproof, especially with complex third-party scripts. Fine-tuning the settings in both Visual Studio and Chrome DevTools can often be the key to resolving these persistent issues.

Another aspect to consider is implementing custom error-handling mechanisms within your Blazor app itself. By adding a global error handler using the event, you can intercept and manage errors before they cause breaks in execution. This method allows you to focus on debugging the actual application code rather than being distracted by external JavaScript errors. The combination of these strategies can significantly improve your debugging experience in Blazor WASM apps.

1. What causes Visual Studio to break on dynamic JavaScript exceptions?
2. Visual Studio breaks when an error occurs in dynamically loaded JavaScript files, typically from third-party libraries like Stripe or Google Maps.
3. How can I prevent Visual Studio from breaking on JavaScript errors?
4. You can disable in the Exception Settings window or turn off JavaScript debugging in Visual Studio's settings.
5. What does "Just My Code" do in Visual Studio?
6. Turning off can prevent Visual Studio from breaking on non-project-related code like third-party scripts.
7. How do I handle third-party errors in a Blazor WASM app?
8. Use a handler to catch and manage exceptions from third-party libraries before they break your application.
9. Can Chrome DevTools help with this issue?
10. Yes, disabling in Chrome DevTools can prevent unnecessary pauses when debugging in Chrome.

Dealing with breakpoints triggered by third-party JavaScript in Visual Studio 2022 can disrupt your work on Blazor WASM apps. Optimizing debugging settings and implementing targeted error handling can significantly improve your development flow, allowing you to focus on core application logic without unnecessary interruptions.

By taking advantage of custom error-handling techniques like and fine-tuning your Visual Studio settings, you can avoid breakpoints caused by third-party scripts and enhance the debugging experience. These steps can save developers time and frustration, resulting in smoother and more efficient debugging sessions.