Allow to pass JSON to NextResponse

[javivelasco]

closes #31196
Co-authored-by: Kiko Beats josefrancisco.verdu@gmail.com

This PR enables support to pass a plain object to NextResponse so that it will be automatically stringified along with a content-type header set to application/json. With this we can, instead of doing:

new Response(JSON.stringify({ message: 'hi' }), {
  headers: {
    'content-type': 'application/json'
  }
})

We can go with:

new NextResponse({ message: 'hi' })

Bug

• Related issues linked using fixes #number
• Integration tests added
• Errors have helpful link attached, see contributing.md

Feature

• Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
• Related issues linked using fixes #number
• Integration tests added
• Documentation added
• Telemetry added. In case of a feature if it's used or not.
• Errors have helpful link attached, see contributing.md

Documentation / Examples

• Make sure the linting passes by running yarn lint

[ijjk]

Stats from current PR

Default Build (Increase detected ⚠️)

General Overall increase ⚠️

	vercel/next.js canary	javivelasco/next.js support/response-json	Change
buildDuration	17.9s	18.4s	⚠️ +473ms
buildDurationCached	3.7s	3.7s	-4ms
nodeModulesSize	332 MB	332 MB	⚠️ +979 B

Page Load Tests Overall increase ✓

	vercel/next.js canary	javivelasco/next.js support/response-json	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.899	2.957	⚠️ +0.06
/ avg req/sec	862.24	845.41	⚠️ -16.83
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.393	1.364	-0.03
/error-in-render avg req/sec	1794.73	1832.48	+37.75

Client Bundles (main, webpack, commons)

	vercel/next.js canary	javivelasco/next.js support/response-json	Change
450.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.2 kB	42.2 kB	✓
main-HASH.js gzip	28 kB	28 kB	✓
webpack-HASH.js gzip	1.45 kB	1.45 kB	✓
Overall change	71.9 kB	71.9 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	javivelasco/next.js support/response-json	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	javivelasco/next.js support/response-json	Change
_app-HASH.js gzip	1.23 kB	1.23 kB	✓
_error-HASH.js gzip	194 B	194 B	✓
amp-HASH.js gzip	312 B	312 B	✓
css-HASH.js gzip	327 B	327 B	✓
dynamic-HASH.js gzip	2.38 kB	2.38 kB	✓
head-HASH.js gzip	350 B	350 B	✓
hooks-HASH.js gzip	635 B	635 B	✓
image-HASH.js gzip	4.44 kB	4.44 kB	✓
index-HASH.js gzip	263 B	263 B	✓
link-HASH.js gzip	1.87 kB	1.87 kB	✓
routerDirect..HASH.js gzip	321 B	321 B	✓
script-HASH.js gzip	383 B	383 B	✓
withRouter-HASH.js gzip	318 B	318 B	✓
334f979574ae..6f4.css gzip	106 B	106 B	✓
Overall change	13.1 kB	13.1 kB	✓

Client Build Manifests

	vercel/next.js canary	javivelasco/next.js support/response-json	Change
_buildManifest.js gzip	459 B	459 B	✓
Overall change	459 B	459 B	✓

Rendered Page Sizes

	vercel/next.js canary	javivelasco/next.js support/response-json	Change
index.html gzip	522 B	522 B	✓
link.html gzip	535 B	535 B	✓
withRouter.html gzip	515 B	515 B	✓
Overall change	1.57 kB	1.57 kB	✓

---

Default Build with SWC (Decrease detected ✓)

General Overall increase ⚠️

	vercel/next.js canary	javivelasco/next.js support/response-json	Change
buildDuration	19.6s	19.5s	-18ms
buildDurationCached	3.6s	3.7s	⚠️ +59ms
nodeModulesSize	332 MB	332 MB	⚠️ +979 B

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	javivelasco/next.js support/response-json	Change
/ failed reqs	0	0	✓
/ total time (seconds)	2.955	2.941	-0.01
/ avg req/sec	845.99	850.03	+4.04
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.335	1.384	⚠️ +0.05
/error-in-render avg req/sec	1873.07	1806.84	⚠️ -66.23

Client Bundles (main, webpack, commons)

	vercel/next.js canary	javivelasco/next.js support/response-json	Change
450.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.3 kB	42.3 kB	✓
main-HASH.js gzip	28.2 kB	28.2 kB	✓
webpack-HASH.js gzip	1.43 kB	1.43 kB	✓
Overall change	72.1 kB	72.1 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	javivelasco/next.js support/response-json	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	javivelasco/next.js support/response-json	Change
_app-HASH.js gzip	1.22 kB	1.22 kB	✓
_error-HASH.js gzip	180 B	180 B	✓
amp-HASH.js gzip	305 B	305 B	✓
css-HASH.js gzip	321 B	321 B	✓
dynamic-HASH.js gzip	2.38 kB	2.38 kB	✓
head-HASH.js gzip	342 B	342 B	✓
hooks-HASH.js gzip	622 B	622 B	✓
image-HASH.js gzip	4.46 kB	4.46 kB	✓
index-HASH.js gzip	256 B	256 B	✓
link-HASH.js gzip	1.91 kB	1.91 kB	✓
routerDirect..HASH.js gzip	314 B	314 B	✓
script-HASH.js gzip	375 B	375 B	✓
withRouter-HASH.js gzip	309 B	309 B	✓
334f979574ae..6f4.css gzip	106 B	106 B	✓
Overall change	13.1 kB	13.1 kB	✓

Client Build Manifests

	vercel/next.js canary	javivelasco/next.js support/response-json	Change
_buildManifest.js gzip	460 B	460 B	✓
Overall change	460 B	460 B	✓

Rendered Page Sizes

	vercel/next.js canary	javivelasco/next.js support/response-json	Change
index.html gzip	521 B	521 B	✓
link.html gzip	534 B	534 B	✓
withRouter.html gzip	515 B	515 B	✓
Overall change	1.57 kB	1.57 kB	✓

Commit: 888234c

[ijjk]

Can we update the doc here mentioning this is specific to NextResponse and isn't specific to the Response API.

Also just an idea but would it make sense to have this be a separate static method like NextResponse.json() instead so that we don't have to keep updating this check with the default handled types?

[javivelasco]

I kind of like that idea better 🤔 It makes sense considering .rewrite and .redirect are doing a very similar thing. WDYT @Kikobeats ?

[Kikobeats]

I like the idea 👍