feat: add Response.json

lib/fetch/response.js

@@ -5,7 +5,7 @@ const { AbortError } = require('../core/errors')
 const { extractBody, cloneBody, mixinBody } = require('./body')
 const util = require('../core/util')
 const { kEnumerableProperty } = util
-const { responseURL, isValidReasonPhrase, toUSVString, isCancelled, isAborted } = require('./util')
+const { responseURL, isValidReasonPhrase, toUSVString, isCancelled, isAborted, serializeJavascriptValueToJSONString } = require('./util')
 const {
   redirectStatus,
   nullBodyStatus,
@@ -35,6 +35,50 @@ class Response {
     return responseObject
   }
 
+  // https://fetch.spec.whatwg.org/#dom-response-json
+  static json (data, init = {}) {
+    if (arguments.length === 0) {
+      throw new TypeError(
+        'Failed to execute \'json\' on \'Response\': 1 argument required, but 0 present.'
+      )
+    }
+
+    if (init === null || typeof init !== 'object') {
+      throw new TypeError(
+        `Failed to execute 'json' on 'Response': init must be a RequestInit, found ${typeof init}.`
+      )
+    }
+
+    init = {
+      status: 200,
+      statusText: '',
+      headers: new HeadersList(),
+      ...init
+    }
+
+    // 1. Let bytes the result of running serialize a JavaScript value to JSON bytes on data.
+    const bytes = new TextEncoder('utf-8').encode(
+      serializeJavascriptValueToJSONString(data)
+    )
+
+    // 2. Let body be the result of extracting bytes.
+    const body = extractBody(bytes)
+
+    // 3. Let responseObject be the result of creating a Response object, given a new response,
+    //    "response", and this’s relevant Realm.
+    const relevantRealm = { settingsObject: {} }
+    const responseObject = new Response()
+    responseObject[kRealm] = relevantRealm
+    responseObject[kHeaders][kGuard] = 'response'
+    responseObject[kHeaders][kRealm] = relevantRealm
+
+    // 4. Perform initialize a response given responseObject, init, and (body, "application/json").
+    initializeResponse(responseObject, init, { body: body[0], type: 'application/json' })
+
+    // 5. Return responseObject.
+    return responseObject
+  }
+
   // Creates a redirect Response that redirects to url with status status.
   static redirect (...args) {
     const relevantRealm = { settingsObject: {} }
@@ -105,76 +149,28 @@ class Response {
     // TODO
     this[kRealm] = { settingsObject: {} }
 
-    // 1. If init["status"] is not in the range 200 to 599, inclusive, then
-    // throw a RangeError.
-    if ('status' in init && init.status !== undefined) {
-      if (!Number.isFinite(init.status)) {
-        throw new TypeError()
-      }
-
-      if (init.status < 200 || init.status > 599) {
-        throw new RangeError(
-          `Failed to construct 'Response': The status provided (${init.status}) is outside the range [200, 599].`
-        )
-      }
-    }
-
-    if ('statusText' in init && init.statusText !== undefined) {
-      // 2. If init["statusText"] does not match the reason-phrase token
-      // production, then throw a TypeError.
-      // See, https://datatracker.ietf.org/doc/html/rfc7230#section-3.1.2:
-      //   reason-phrase  = *( HTAB / SP / VCHAR / obs-text )
-      if (!isValidReasonPhrase(String(init.statusText))) {
-        throw new TypeError('Invalid statusText')
-      }
-    }
-
-    // 3. Set this’s response to a new response.
+    // 1. Set this’s response to a new response.
     this[kState] = makeResponse({})
 
-    // 4. Set this’s headers to a new Headers object with this’s relevant
+    // 2. Set this’s headers to a new Headers object with this’s relevant
     // Realm, whose header list is this’s response’s header list and guard
     // is "response".
     this[kHeaders] = new Headers()
     this[kHeaders][kGuard] = 'response'
     this[kHeaders][kHeadersList] = this[kState].headersList
     this[kHeaders][kRealm] = this[kRealm]
 
-    // 5. Set this’s response’s status to init["status"].
-    if ('status' in init && init.status !== undefined) {
-      this[kState].status = init.status
-    }
-
-    // 6. Set this’s response’s status message to init["statusText"].
-    if ('statusText' in init && init.statusText !== undefined) {
-      this[kState].statusText = String(init.statusText)
-    }
-
-    // 7. If init["headers"] exists, then fill this’s headers with init["headers"].
-    if ('headers' in init) {
-      fill(this[kState].headersList, init.headers)
-    }
+    // 3. Let bodyWithType be null.
+    let bodyWithType = null
 
-    // 8. If body is non-null, then:
+    // 4. If body is non-null, then set bodyWithType to the result of extracting body.
     if (body != null) {
-      // 1. If init["status"] is a null body status, then throw a TypeError.
-      if (nullBodyStatus.includes(init.status)) {
-        throw new TypeError('Response with null body status cannot have body')
-      }
-
-      // 2. Let Content-Type be null.
-      // 3. Set this’s response’s body and Content-Type to the result of
-      // extracting body.
-      const [extractedBody, contentType] = extractBody(body)
-      this[kState].body = extractedBody
-
-      // 4. If Content-Type is non-null and this’s response’s header list does
-      // not contain `Content-Type`, then append `Content-Type`/Content-Type
-      // to this’s response’s header list.
-      if (contentType && !this.headers.has('content-type')) {
-        this.headers.append('content-type', contentType)
-      }
+      const [extractedBody, type] = extractBody(body)
+      bodyWithType = { body: extractedBody, type }
     }
+
+    // 5. Perform initialize a response given this, init, and bodyWithType.
+    initializeResponse(this, init, bodyWithType)
   }
 
   get [Symbol.toStringTag] () {
@@ -473,6 +469,57 @@ function makeAppropriateNetworkError (fetchParams) {
     : makeNetworkError(fetchParams.controller.terminated.reason)
 }
 
+// https://whatpr.org/fetch/1392.html#initialize-a-response
+function initializeResponse (response, init, body) {
+  // 1. If init["status"] is not in the range 200 to 599, inclusive, then
+  //    throw a RangeError.
+  if (init.status != null && (init.status < 200 || init.status > 599)) {
+    throw new RangeError('init["status"] must be in the range of 200 to 599, inclusive.')
+  }
+
+  // 2. If init["statusText"] does not match the reason-phrase token production,
+  //    then throw a TypeError.
+  if ('statusText' in init && init.statusText != null) {
+    // See, https://datatracker.ietf.org/doc/html/rfc7230#section-3.1.2:
+    //   reason-phrase  = *( HTAB / SP / VCHAR / obs-text )
+    if (!isValidReasonPhrase(String(init.statusText))) {
+      throw new TypeError('Invalid statusText')
+    }
+  }
+
+  // 3. Set response’s response’s status to init["status"].
+  if ('status' in init && init.status != null) {
+    response[kState].status = init.status
+  }
+
+  // 4. Set response’s response’s status message to init["statusText"].
+  if ('statusText' in init && init.statusText != null) {
+    response[kState].statusText = init.statusText
+  }
+
+  // 5. If init["headers"] exists, then fill response’s headers with init["headers"].
+  if ('headers' in init && init.headers != null) {
+    fill(response[kState].headersList, init.headers)
+  }
+
+  // 6. If body was given, then:
+  if (body) {
+    // 1. If response's status is a null body status, then throw a TypeError.
+    if (nullBodyStatus.includes(response.status)) {
+      throw new TypeError()
+    }
+
+    // 2. Set response's body to body's body.
+    response[kState].body = body.body
+
+    // 3. If body's type is non-null and response's header list does not contain
+    //    `Content-Type`, then append (`Content-Type`, body's type) to response's header list.
+    if (body.type != null && !response[kState].headersList.has('Content-Type')) {
+      response[kState].headersList.append('content-type', body.type)
+    }
+  }
+}
+
 module.exports = {
   makeNetworkError,
   makeResponse,

lib/fetch/util.js

@@ -3,6 +3,7 @@
 const { redirectStatus } = require('./constants')
 const { performance } = require('perf_hooks')
 const { isBlobLike, toUSVString, ReadableStreamFrom } = require('../core/util')
+const assert = require('assert')
 
 let File
 
@@ -384,6 +385,23 @@ function normalizeMethod (method) {
     : method
 }
 
+// https://infra.spec.whatwg.org/#serialize-a-javascript-value-to-a-json-string
+function serializeJavascriptValueToJSONString (value) {
+  // 1. Let result be ? Call(%JSON.stringify%, undefined, « value »).
+  const result = JSON.stringify(value)
+
+  // 2. If result is undefined, then throw a TypeError.
+  if (result === undefined) {
+    throw new TypeError('Value is not JSON serializable')
+  }
+
+  // 3. Assert: result is a string.
+  assert(typeof result === 'string')
+
+  // 4. Return result.
+  return result
+}
+
 module.exports = {
   isAborted,
   isCancelled,
@@ -413,5 +431,6 @@ module.exports = {
   isValidReasonPhrase,
   sameOrigin,
   CORBCheck,
-  normalizeMethod
+  normalizeMethod,
+  serializeJavascriptValueToJSONString
 }

test/fetch/response-json.js

@@ -0,0 +1,113 @@
+'use strict'
+
+const { test } = require('tap')
+const { Response } = require('../../')
+
+// https://github.com/web-platform-tests/wpt/pull/32825/
+
+const APPLICATION_JSON = 'application/json'
+const FOO_BAR = 'foo/bar'
+
+const INIT_TESTS = [
+  [undefined, 200, '', APPLICATION_JSON, {}],
+  [{ status: 400 }, 400, '', APPLICATION_JSON, {}],
+  [{ statusText: 'foo' }, 200, 'foo', APPLICATION_JSON, {}],
+  [{ headers: {} }, 200, '', APPLICATION_JSON, {}],
+  [{ headers: { 'content-type': FOO_BAR } }, 200, '', FOO_BAR, {}],
+  [{ headers: { 'x-foo': 'bar' } }, 200, '', APPLICATION_JSON, { 'x-foo': 'bar' }]
+]
+
+test('Check response returned by static json() with init', async (t) => {
+  for (const [init, expectedStatus, expectedStatusText, expectedContentType, expectedHeaders] of INIT_TESTS) {
+    const response = Response.json('hello world', init)
+    t.equal(response.type, 'default', "Response's type is default")
+    t.equal(response.status, expectedStatus, "Response's status is " + expectedStatus)
+    t.equal(response.statusText, expectedStatusText, "Response's statusText is " + JSON.stringify(expectedStatusText))
+    t.equal(response.headers.get('content-type'), expectedContentType, "Response's content-type is " + expectedContentType)
+    for (const key in expectedHeaders) {
+      t.equal(response.headers.get(key), expectedHeaders[key], "Response's header " + key + ' is ' + JSON.stringify(expectedHeaders[key]))
+    }
+
+    const data = await response.json()
+    t.equal(data, 'hello world', "Response's body is 'hello world'")
+  }
+
+  t.end()
+})
+
+test('Throws TypeError when calling static json() with an invalid status', (t) => {
+  const nullBodyStatus = [204, 205, 304]
+
+  for (const status of nullBodyStatus) {
+    t.throws(() => {
+      Response.json('hello world', { status })
+    }, TypeError, `Throws TypeError when calling static json() with a status of ${status}`)
+  }
+
+  t.end()
+})
+
+test('Check static json() encodes JSON objects correctly', async (t) => {
+  const response = Response.json({ foo: 'bar' })
+  const data = await response.json()
+  t.equal(typeof data, 'object', "Response's json body is an object")
+  t.equal(data.foo, 'bar', "Response's json body is { foo: 'bar' }")
+
+  t.end()
+})
+
+test('Check static json() throws when data is not encodable', (t) => {
+  t.throws(() => {
+    Response.json(Symbol('foo'))
+  }, TypeError)
+
+  t.end()
+})
+
+test('Check static json() throws when data is circular', (t) => {
+  const a = { b: 1 }
+  a.a = a
+
+  t.throws(() => {
+    Response.json(a)
+  }, TypeError)
+
+  t.end()
+})
+
+test('Check static json() propagates JSON serializer errors', (t) => {
+  class CustomError extends Error {
+    name = 'CustomError'
+  }
+
+  t.throws(() => {
+    Response.json({ get foo () { throw new CustomError('bar') } })
+  }, CustomError)
+
+  t.end()
+})
+
+// note: these tests are not part of any WPTs
+test('unserializable values', (t) => {
+  t.throws(() => {
+    Response.json(Symbol('symbol'))
+  }, TypeError)
+
+  t.throws(() => {
+    Response.json(undefined)
+  }, TypeError)
+
+  t.throws(() => {
+    Response.json()
+  }, TypeError)
+
+  t.end()
+})
+
+test('invalid init', (t) => {
+  t.throws(() => {
+    Response.json(null, 3)
+  }, TypeError)
+
+  t.end()
+})

test/fetch/response.js

@@ -28,7 +28,7 @@ test('arg validation', (t) => {
     new Response(null, {
       status: '600'
     })
-  }, TypeError)
+  }, RangeError)
   t.throws(() => {
     // eslint-disable-next-line
     new Response(null, {

test/types/fetch.test-d.ts

@@ -108,12 +108,19 @@ expectType<Response>(new Response(new BigInt64Array(), responseInit))
 expectType<Response>(new Response(new BigUint64Array(), responseInit))
 expectType<Response>(new Response(new ArrayBuffer(0), responseInit))
 expectType<Response>(Response.error())
+expectType<Response>(Response.json({ a: 'b' }))
+expectType<Response>(Response.json({}, { status: 200 }))
+expectType<Response>(Response.json({}, { statusText: 'OK' }))
+expectType<Response>(Response.json({}, { headers: {} }))
+expectType<Response>(Response.json(null))
 expectType<Response>(Response.redirect('https://example.com', 301))
 expectType<Response>(Response.redirect('https://example.com', 302))
 expectType<Response>(Response.redirect('https://example.com', 303))
 expectType<Response>(Response.redirect('https://example.com', 307))
 expectType<Response>(Response.redirect('https://example.com', 308))
 expectError(Response.redirect('https://example.com', NaN))
+expectError(Response.json())
+expectError(Response.json(null, 3))
 
 expectType<void>(headers.append('key', 'value'))
 expectType<void>(headers.delete('key'))

types/fetch.d.ts

@@ -199,5 +199,6 @@ export declare class Response implements BodyMixin {
   readonly clone: () => Response
 
   static error (): Response
+  static json(data: any, init?: ResponseInit): Response
   static redirect (url: string | URL, status: ResponseRedirectStatus): Response
 }