Default Types

Default Output

By default, the response data will always be of type unknown. If you want to customize the default type you can pass the defaultOutput option to the createFetch function. Note: When you supply a custom output schema using a Standard Schema validator (for example, zod or any alternative), the provided output schema will override the defaultOutput type. This approach offers a strongly typed solution without locking you to a single library.

This only serves as a type for the response data it's not used as a validation schema.

fetch.ts

import { createFetch } from "@better-fetch/fetch";
// Example using zod (or any Standard Schema compliant library)
import { z } from "zod"; 
 
const $fetch = createFetch({
    baseURL: "https://jsonplaceholder.typicode.com",
    defaultOutput: z.any(),
})
 
const { data, error } = await $fetch("/todos/1")
 
 Hover over the data object to see the type

If you define output schema, the default output type will be ignored.

fetch.ts

import { createFetch } from "@better-fetch/fetch";
import { z } from "zod";
 
const $fetch = createFetch({
    baseURL: "https://jsonplaceholder.typicode.com",
    defaultOutput: z.any(),
});
 
const { data, error } = await $fetch("/todos/1", {
    output: z.object({
        userId: z.string(),
        id: z.number(),
        title: z.string(),
        completed: z.boolean(),
    }),
})
 Hover over the data object to see the type

Default error

The default error type is:

{ status: number, statusText: string, message?: string }

If you want a custom error type, you can pass a defaultError option to the createFetch function. Remember: Your custom error type builds on top of the default properties, and if your API returns a JSON error, // it will be merged with your definition.

The status and statusText properties are always defined. Your custom error definitions are only inferred if the API returns a JSON error object.

fetch.ts

import { createFetch } from "@better-fetch/fetch";
import { z } from "zod"; // Example only
 
const $fetch = createFetch({
    baseURL: "https://jsonplaceholder.typicode.com",
    defaultError: z.object({
        message: z.string().optional(),
        error: z.string(),
    }),
})
 
const { data, error } = await $fetch("/todos/1")
 Hover over the error object to see the type

Default Types

Default Output

Default error

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