How do I type requests in TypeScript using fetch?

How do I type requests in TypeScript using fetch?

You can use TypeScript's type annotations to define the shape of the data you're expecting. For example, you can create an interface for your response data.

Can you show me an example of that?

Sure! Here's a simple example:

interface User {
  id: number;
  name: string;
}

async function fetchUser(userId: number): Promise<User> {
  const response = await fetch(`https://api.example.com/users/${userId}`);
  return response.json();
}

What if the response can be an error?

You can use a union type to handle both success and error responses. For example:

type ApiResponse = User | { error: string };

async function fetchUser(userId: number): Promise<ApiResponse> {
  const response = await fetch(`https://api.example.com/users/${userId}`);
  if (!response.ok) {
    return { error: 'User not found' };
  }
  return response.json();
}