Скачать или смотреть Solving the Typescript Error When Switching from axios to fetch

Discover how to fix the `Typescript` error you encounter while switching from `axios` to `fetch`. This post provides a step-by-step guide on using type definitions for your API response.
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Switching from Axios to Fetch: Resolving Type Errors in TypeScript

Switching libraries in your codebase can sometimes be a bumpy ride, especially when dealing with type systems like TypeScript. If you're transitioning from Axios to Fetch and encountering issues with type errors, you’re not alone. In this guide, we will explore one such problem and how to effectively resolve it.

The Problem: TypeScript Error

The issue arises when trying to destructure data returned from a Fetch request. With Axios, you might have written code similar to this:

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

However, when you switch to Fetch, your code might look like this:

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

As you can see, while Axios automatically infers types for the response, Fetch doesn't. Here’s where the error comes in:

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

Understanding the Error

When using Fetch's response.json(), TypeScript infers the type as Promise<unknown>. This means that TypeScript doesn't understand the shape of the data returned by your API. Thus, it raises an error when you attempt to access library, as it can't guarantee that such a property exists on an unknown type.

The Solution: Type Casting

To solve this problem, you need to tell TypeScript what to expect from the JSON response. Here’s how you can do it:

Step 1: Define an Interface for Your Response

Creating an interface allows you to specify the structure of the expected response clearly. For your API, you might define it like this:

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

Step 2: Cast the Response

Next, when you’re parsing the response, you can cast it to your defined interface like so:

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

Complete Function Example

Here’s your complete function using Fetch with type casting:

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

Conclusion

Switching from Axios to Fetch in your TypeScript application can introduce some complications, particularly when it comes to type safety. By defining an interface for your expected response and properly casting it, you can eliminate the type errors that arise from TypeScript's strict typing.

This method not only resolves your immediate issue but also keeps your code clean and maintainable. As you continue to develop with TypeScript, embracing its type system will yield significant benefits in the long run.

If you encounter any other difficulties or have further questions, feel free to leave a comment below! Happy coding!