Response

`Response.json`

Returns a new Response object with a JSON-encoded body and the Content-Type header set to application/json

Syntax

JavaScript

Response.json(data, init?)

Parameters

Parameter	Type	Description
data	any	The data to JSON-encode as the response body
init	ResponseInit	Optional response init (status, headers)

Return Value

A new Response object with JSON body

Examples

Basic Usage

const response = Response.json({ message: 'Hello' })
const data = await response.json()
console.log(data.message) // 'Hello'

Practical Example

const errorResponse = Response.json(
  { error: 'Not found' },
  { status: 404 }
)
console.log(errorResponse.status) // 404

Advanced Usage

function apiResponse<T>(data: T, status = 200) {
  return Response.json(data, { status })
}
const res = apiResponse({ users: ['Alice', 'Bob'] })
console.log(await res.json())

Understanding Response.json

The Response.json method in JavaScript returns a new Response object with a JSON-encoded body and the Content-Type header set to application/json. It belongs to the Response object and is one of the most widely used methods for working with response values in modern JavaScript and TypeScript applications.

The method signature is Response.json(data, init?). It accepts 2 parameters: data, init. When called, it returns a new response object with json body. Understanding when and how to use json() helps you write more expressive, readable code.

Common use cases for Response.json include data transformation, input validation, API response processing, and building reusable utility functions. It works well alongside related methods like response-constructor, fetch-response-json, request-constructor, enabling you to chain operations together for complex data manipulation pipelines.

Supported in Chrome 105+, Firefox 115+, Safari 17+, Edge 105+, and Node.js 20+.