Use consistent resolve extensions alias for compiler

[timneutkens]

What?

Changes the default resolve extensions to be consistent between server/client compilation.

Currently browser prefers .mjs then .js and the server compiler prefers .js then .mjs.

I added that behavior back in 2018 before mjs/cjs extensions were fully baked and many npm libraries had incorrect usage of it (PR: #5898).

In the new setup with ESM resolving in Node.js writing out the full extension is required for .mjs files, meaning this "magic resolving" of a file to .mjs is no longer correct. In the future we'll likely want to remove .mjs from the default list of resolve extensions to align with the Node.js ESM resolver a bit more.

For now we have to keep it in order to not break existing applications that rely on that behavior, an example of that seems to be contentlayer.

How?

Removed the condition and aligned it on a single list instead of separate lists.

[timneutkens]

Current dependencies on/for this PR:

• canary
  • PR Use consistent resolve extensions alias for compiler #58725 👈

This stack of pull requests is managed by Graphite.

[ijjk]

Tests Passed

[ijjk]

Stats from current PR

Default Build

General

	vercel/next.js canary	vercel/next.js 11-21-Use_consistent_resolve_extensions_alias_for_compiler	Change
buildDuration	10.1s	10.3s	⚠️ +202ms
buildDurationCached	5.8s	5.8s	N/A
nodeModulesSize	199 MB	199 MB	N/A
nextStartRea..uration (ms)	424ms	425ms	N/A

Client Bundles (main, webpack)

	vercel/next.js canary	vercel/next.js 11-21-Use_consistent_resolve_extensions_alias_for_compiler	Change
199-HASH.js gzip	28.7 kB	28.7 kB	N/A
3f784ff6-HASH.js gzip	53.3 kB	53.3 kB	✓
494.HASH.js gzip	180 B	181 B	N/A
framework-HASH.js gzip	45.2 kB	45.2 kB	✓
main-app-HASH.js gzip	241 B	239 B	N/A
main-HASH.js gzip	31.7 kB	31.7 kB	N/A
webpack-HASH.js gzip	1.7 kB	1.7 kB	✓
Overall change	100 kB	100 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	vercel/next.js 11-21-Use_consistent_resolve_extensions_alias_for_compiler	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	vercel/next.js 11-21-Use_consistent_resolve_extensions_alias_for_compiler	Change
_app-HASH.js gzip	194 B	195 B	N/A
_error-HASH.js gzip	182 B	181 B	N/A
amp-HASH.js gzip	501 B	503 B	N/A
css-HASH.js gzip	322 B	323 B	N/A
dynamic-HASH.js gzip	2.5 kB	2.5 kB	✓
edge-ssr-HASH.js gzip	253 B	255 B	N/A
head-HASH.js gzip	348 B	347 B	N/A
hooks-HASH.js gzip	369 B	368 B	N/A
image-HASH.js gzip	4.28 kB	4.27 kB	N/A
index-HASH.js gzip	256 B	256 B	✓
link-HASH.js gzip	2.61 kB	2.6 kB	N/A
routerDirect..HASH.js gzip	311 B	311 B	✓
script-HASH.js gzip	384 B	383 B	N/A
withRouter-HASH.js gzip	307 B	308 B	N/A
1afbb74e6ecf..834.css gzip	106 B	106 B	✓
Overall change	3.17 kB	3.17 kB	✓

Client Build Manifests

	vercel/next.js canary	vercel/next.js 11-21-Use_consistent_resolve_extensions_alias_for_compiler	Change
_buildManifest.js gzip	484 B	483 B	N/A
Overall change	0 B	0 B	✓

Rendered Page Sizes

	vercel/next.js canary	vercel/next.js 11-21-Use_consistent_resolve_extensions_alias_for_compiler	Change
index.html gzip	528 B	526 B	N/A
link.html gzip	538 B	540 B	N/A
withRouter.html gzip	522 B	522 B	✓
Overall change	522 B	522 B	✓

Edge SSR bundle Size

	vercel/next.js canary	vercel/next.js 11-21-Use_consistent_resolve_extensions_alias_for_compiler	Change
edge-ssr.js gzip	92.4 kB	92.4 kB	N/A
page.js gzip	145 kB	145 kB	N/A
Overall change	0 B	0 B	✓

Middleware size

	vercel/next.js canary	vercel/next.js 11-21-Use_consistent_resolve_extensions_alias_for_compiler	Change
middleware-b..fest.js gzip	625 B	625 B	✓
middleware-r..fest.js gzip	150 B	151 B	N/A
middleware.js gzip	24.8 kB	24.8 kB	✓
edge-runtime..pack.js gzip	1.92 kB	1.92 kB	✓
Overall change	27.4 kB	27.4 kB	✓

Next Runtimes

	vercel/next.js canary	vercel/next.js 11-21-Use_consistent_resolve_extensions_alias_for_compiler	Change
app-page-exp...dev.js gzip	167 kB	167 kB	✓
app-page-exp..prod.js gzip	93.4 kB	93.4 kB	✓
app-page-tur..prod.js gzip	94.1 kB	94.1 kB	✓
app-page-tur..prod.js gzip	88.7 kB	88.7 kB	✓
app-page.run...dev.js gzip	137 kB	137 kB	✓
app-page.run..prod.js gzip	88 kB	88 kB	✓
app-route-ex...dev.js gzip	23.8 kB	23.8 kB	✓
app-route-ex..prod.js gzip	16.4 kB	16.4 kB	✓
app-route-tu..prod.js gzip	16.5 kB	16.5 kB	✓
app-route-tu..prod.js gzip	16 kB	16 kB	✓
app-route.ru...dev.js gzip	23.2 kB	23.2 kB	✓
app-route.ru..prod.js gzip	16 kB	16 kB	✓
pages-api-tu..prod.js gzip	9.37 kB	9.37 kB	✓
pages-api.ru...dev.js gzip	9.64 kB	9.64 kB	✓
pages-api.ru..prod.js gzip	9.37 kB	9.37 kB	✓
pages-turbo...prod.js gzip	21.8 kB	21.8 kB	✓
pages.runtim...dev.js gzip	22.5 kB	22.5 kB	✓
pages.runtim..prod.js gzip	21.8 kB	21.8 kB	✓
server.runti..prod.js gzip	49.1 kB	49.1 kB	✓
Overall change	924 kB	924 kB	✓

Commit: ab457da

[sokra]

This might be a breaking change in some cases.