Transpilers have revolutionized modern software development, enabling developers to write code in one language and convert it into another while maintaining efficiency and maintainability. One of the most popular language pairs for transpiling is C# and JavaScript, primarily due to the need for seamless integration between server-side logic (C#) and client-side functionality (JavaScript).

But why would a developer want to transpile between these two languages? Here are the 10 most common scenarios where transpiling between C# and JavaScript is beneficial.

 

1. Web Application Development with Blazor and WebAssembly

One of the biggest advancements in recent years is Blazor, a framework that allows developers to write interactive web applications in C# instead of JavaScript. Under the hood, Blazor compiles C# into WebAssembly (WASM), which is then executed in the browser.

How a Transpiler Helps:

• • Converts C# code into JavaScript or WebAssembly so it runs natively in the browser.

• • Allows developers to reuse C# logic instead of rewriting it in JavaScript.

• • Enables full-stack development in C#, reducing the reliance on JavaScript frameworks like React or Angular.
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2. Using C# Business Logic in JavaScript-Based Frontends

Many companies have a large amount of business logic written in C#. If they want to create a modern web frontend using JavaScript frameworks like React, Vue, or Angular, they need a way to convert C# logic to JavaScript.

How a Transpiler Helps:

• • Converts C# classes, methods, and logic into JavaScript.

• • Reduces code duplication by reusing backend logic on the frontend.

• • Improves maintainability by keeping a single source of truth for business rules.

Popular tools for this purpose include Bridge.NET and Blazor with WebAssembly.

 

3. Calling JavaScript Code from C# (Interoperability)

Sometimes, you need to call JavaScript functions from your C# code, especially when using Blazor or other WebAssembly-based applications.

How a Transpiler Helps:

• • Bridges the gap between C# and JavaScript via interop mechanisms.

• • Allows C# code to call JavaScript APIs for tasks like DOM manipulation, calling REST APIs, or using third-party JavaScript libraries.

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  • Some transpilers, like JSInterop in Blazor, make it easy to execute JavaScript code from C#.

4. Converting JavaScript Codebases to C# for Backend Reusability

If you already have an extensive JavaScript codebase but want to move to a C# backend, you may need to convert JavaScript logic into C#.

How a Transpiler Helps:

• • Automatically converts JavaScript business logic into equivalent C# code.

• • Ensures compatibility between legacy JavaScript applications and new C# backends.

• • Reduces manual rewriting effort when migrating large projects.

Tools like JSPredict or custom transpilers can assist with this process.

 

5. Using C# in Node.js for Server-Side JavaScript Applications

Node.js is a popular server-side JavaScript runtime, but some developers prefer writing backend logic in C#. Using a transpiler, it’s possible to run C#-to-JavaScript-transpiled code inside Node.js.

How a Transpiler Helps:

• • Converts C# to JavaScript, allowing developers to run C#-written logic in a Node.js backend.

• • Bridges the gap between .NET-based services and JavaScript microservices.

• • Useful for teams with C# expertise who need to work in a JavaScript-heavy environment.

One example is Bridge.NET, which allows running transpiled C# code inside Node.js.

 

6. Running JavaScript in C# Applications

Some applications require executing JavaScript inside a C# application—for example, when embedding a web browser inside a .NET app using WebView.

How a Transpiler Helps:

• • Converts JavaScript into C# executable code.

• • Enables server-side execution of JavaScript logic within a C# environment.

• • Allows integrating JavaScript UI frameworks inside C# desktop applications.

Popular tools include Jurassic (a JavaScript engine for .NET) and Jint (a .NET JavaScript interpreter).

 

7. Reusing C# Code in JavaScript Mobile Apps

For mobile development, many companies use JavaScript frameworks like React Native, but they may also have existing C# code for business logic.

How a Transpiler Helps:

• • Converts existing C# logic into JavaScript-compatible code.

• • Allows reusing C# backends in a JavaScript-based mobile app.

• • Reduces development time by avoiding code duplication.

This is useful for projects migrating from Xamarin to React Native.

 

8. Converting JavaScript Libraries to C# for .NET Compatibility

Some powerful JavaScript libraries don’t have direct equivalents in C#. Instead of writing everything from scratch, developers use transpilers to convert JavaScript libraries into C#.

How a Transpiler Helps:

• • Converts JavaScript libraries into .NET-compatible C# code.

• • Allows integrating modern JavaScript features into C# applications.

• • Bridges the gap between JavaScript-based and .NET-based ecosystems.

For example, tools like JSIL (JavaScript to C# transpiler) help with such conversions.

 

9. Creating Hybrid Applications with C# and JavaScript

Many applications are hybrid, meaning they use both C# and JavaScript. A common example is Electron.js, where developers use JavaScript for the frontend and C# for backend logic.

How a Transpiler Helps:

• • Converts C# backend logic into JavaScript so it runs in the Electron environment.

• • Enables communication between JavaScript UI components and C# logic.

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  • Reduces development effort by allowing code reuse across layers.

10. Performance Optimization: Choosing the Right Language for Each Task

Some tasks are better suited for JavaScript, while others are better in C#. Using a transpiler allows developers to move code between languages for performance reasons.

How a Transpiler Helps:

• • Moves computationally expensive operations to C# (for efficiency).

• • Converts UI-related logic to JavaScript (for better frontend performance).

• • Enables dynamic language switching to optimize execution time.

For instance, certain machine learning tasks may be written in C# but need to run in a JavaScript environment, making transpilation necessary.

 

Conclusion

Transpiling between C# and JavaScript opens up a world of possibilities for developers. Whether you’re working on web applications, mobile development, backend services, or performance optimizations, using a transpiler can help you bridge the gap between these two powerful languages.

By understanding these common scenarios, you can make an informed decision on when and how to use transpilation to maximize code reuse, maintainability, and efficiency.

Would you like help selecting the best transpiler for your use case? Let us know!