How to Return application/javascript from an ASP.NET Core Controller

Learn how to modify your ASP.NET Core controller to return JavaScript content-type correctly, ensuring seamless integration with your front-end applications.
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How to Return application/javascript from an ASP.NET Core Controller

When working with ASP.NET Core, you may encounter a scenario where you need to call a third-party API that returns a JavaScript function. The challenge arises when you want to return this function to your front-end application with the correct content type as application/javascript. If your controller is returning this content type as plain text instead, don't worry! In this guide, we will guide you through the solution step by step.

The Problem

In the code snippet provided, the developer is making an HTTP request to a third-party API and is subsequently trying to send the response back to the front-end. However, the content type of the response ends up being plain text rather than the desired application/javascript. To better understand the problem, here's the relevant part of the original code:

[[See Video to Reveal this Text or Code Snippet]]

Although the Accept header is set to accept application/javascript, the controller is returning the response without specifying its content type explicitly.

The Solution

To correctly return the response with the proper content type, you should use the Content() method when returning the response from your controller. This allows you to specify the content type directly. Here’s how you can modify your code:

Step-by-Step Change

Get the Response as a String: Continue the same way you retrieve the response from the API.

Use the Content() Method: Instead of returning Ok(responseString), use Content(responseString, "application/javascript").

Here’s the revised version of your method:

[[See Video to Reveal this Text or Code Snippet]]

Explanation

Content() Method: This method creates a ContentResult with the provided content and content type. By passing "application/javascript", you ensure that the client receives the correct response format.

Why This Works: The original return statement Ok(responseString) uses the default content type of text/plain if no content type is specified. By using Content(), you are explicitly stating what type of content you are returning.

Conclusion

In summary, returning the correct content type for JavaScript functionality in an ASP.NET Core controller is straightforward once you use the right methods. By using the Content() method, you can ensure that the front-end application receives the JavaScript function as intended. This small adjustment will improve your API's responsiveness and make it easier for front-end developers to integrate with your backend services.

Now, you can confidently return JavaScript content types in your ASP.NET Core application and streamline your development process!