fix(next/image): render valid html according to W3C #33825

theoludwig · 2022-01-31T13:59:30Z

Bug

Fixes next/image produces invalid HTML according to W3C (again) #33809
Related to use text data url instead of base64 for shorter encoding #33218
Integration tests added: Usage of html-validator to validate the HTML.
Errors have helpful link attached, see contributing.md (N/A)

ijjk · 2022-01-31T14:08:35Z

test/integration/image-component/valid-w3c-html/test/index.test.js

+    await waitFor(1000)
+    expect(await browser.hasElementByCssSelector('img')).toBeTruthy()
+    const url = await browser.url()
+    const result = await validateHTML({


We could add this to the existing image-component test suite here instead and ensure the different layouts all validate correctly

Good idea, done! 👍

To keep things simple, I still added a new page /valid-html-w3c in the default folder.

This allows to support Node.js v12 (ref: zrrrzzt/html-validator@c3a11fa)

styfle · 2022-01-31T15:17:21Z

package.json

@@ -112,6 +113,7 @@
    "get-port": "5.1.1",
    "glob": "7.1.6",
    "gzip-size": "5.1.1",
+    "html-validator": "5",


Any reason this isn't using the latest version, 6?

Yes, v6 dropped support for Node.js v12 (ref: zrrrzzt/html-validator@c3a11fa), hence failing the test using Node.js v12.
But Next.js support Node.js >= 12.22.0.

But yes instead to use 5, we could use 5.1.18. 👍

test/integration/image-component/default/test/index.test.js

Co-authored-by: Steven <[email protected]>

test/integration/image-component/default/pages/valid-html-w3c.js

)" This reverts commit 628e6ac.

theoludwig · 2022-01-31T19:30:11Z

There are a few failing tests, even if this PR fixes the W3C issue, it breaks a lot of things!

Instead, to do the fix by adding + instead of space, I reverted PR #33218, I think it is the easiest fix.
I think that using base64 encoding is still fine, now that we have the integration test to avoid regression again, it might be safer to do #33218, if it is still really wanted but that would probably be in another PR.

Could you rerun the GitHub Actions to see if indeed reverting #33218 fixes the issue? 😄

styfle · 2022-01-31T20:31:57Z

test/integration/image-component/default/test/index.test.js

+  it('should be valid W3C HTML', async () => {
+    let browser
+    try {
+      browser = await webdriver(appPort, '/valid-html-w3c')


Lets loop through every page here to ensure all usages of the image component are valid HTML

I will try but that requires a lot of changes to these pages because a lot of them are not valid W3C because of all kinds of errors like duplicated IDs etc. And I feel like it's unrelated to this PR.

Testing only with the /valid-html-w3c page keeps things simple and only test what is really needed.
Will keep you updated! 👍

styfle · 2022-01-31T20:33:34Z

You should be able to run the tests locally with yarn testheadless test/integration/image-optimizer/test/index.test.js

theoludwig · 2022-01-31T21:12:49Z

You should be able to run the tests locally with yarn testheadless test/integration/image-optimizer/test/index.test.js

Thanks for the tip! I was using this command: node './node_modules/.bin/jest' './test/integration/image-component/default/test/index.test.js' -t 'Image Component Tests' but I had issues with errors like that: connect ECONNREFUSED 127.0.0.1:42635.

It seems like all the tests pass except on the Azure side (no idea why it's completely unrelated tests that fail).

styfle · 2022-01-31T21:20:04Z

Lets make sure to run validation on all pages. You can update the test to do fs.readdir() to find all the pages in that test fixture.

theoludwig · 2022-01-31T21:36:04Z

Yes, here is what I did:

it('should be valid W3C HTML', async () => {
  let browser
  const pages = readdirSync(join(appDir, 'pages'))
    .filter((page) => {
      return page !== '_document.js' && page !== '_app.js'
    })
    .map((page) => {
      return `/${page.replace(/\.js$/, '')}`
    })
  for (const page of pages) {
    console.log(`Validating ${page}`)
    try {
      browser = await webdriver(appPort, page)
      await waitFor(1000)
      expect(await browser.hasElementByCssSelector('img')).toBeTruthy()
      const url = await browser.url()
      const result = await validateHTML({
        url,
        format: 'json',
        isLocal: true,
      })
      expect(result.messages).toEqual([])
    } finally {
      if (browser) {
        await browser.close()
      }
    }
  }
})

It is working, but there are so many W3C errors (whereas /valid-html-w3c has no error)...
A few examples include:

Attribute “imagesrcset” not allowed on element “link” at this point.
Element “link” is missing one or more of the following attributes: “href”, “resource”.
An “img” element must have an “alt” attribute, except under certain conditions. For details, consult guidance on providing text alternatives for images.
Duplicate ID “blurry-placeholder-with-lazy”.

So it makes sense to only test that we render valid HTML when the user correctly use next/image.
For example: /missing-src is of course not valid HTML because the user didn't specified src.

styfle

Makes sense, we can add it in a follow up PR. Thanks!

styfle

I encoded space as %20 now it passes validation 👍

ijjk · 2022-01-31T23:33:14Z

Stats from current PR

Default Build (Decrease detected ✓)

General Overall decrease ✓

	vercel/next.js canary	Divlo/next.js fix/next-image-render-valid-html-w3c	Change
buildDuration	14.6s	14.7s	⚠️ +102ms
buildDurationCached	3.7s	3.7s	-36ms
nodeModulesSize	358 MB	358 MB	-95 B

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	Divlo/next.js fix/next-image-render-valid-html-w3c	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.439	3.439	✓
/ avg req/sec	727.06	726.95	⚠️ -0.11
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.561	1.59	⚠️ +0.03
/error-in-render avg req/sec	1601.05	1572.09	⚠️ -28.96

Client Bundles (main, webpack, commons)

	vercel/next.js canary	Divlo/next.js fix/next-image-render-valid-html-w3c	Change
450.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.2 kB	42.2 kB	✓
main-HASH.js gzip	27.2 kB	27.2 kB	✓
webpack-HASH.js gzip	1.44 kB	1.44 kB	✓
Overall change	71 kB	71 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	Divlo/next.js fix/next-image-render-valid-html-w3c	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages Overall increase ⚠️

	vercel/next.js canary	Divlo/next.js fix/next-image-render-valid-html-w3c	Change
_app-HASH.js gzip	1.37 kB	1.37 kB	✓
_error-HASH.js gzip	194 B	194 B	✓
amp-HASH.js gzip	312 B	312 B	✓
css-HASH.js gzip	326 B	326 B	✓
dynamic-HASH.js gzip	2.37 kB	2.37 kB	✓
head-HASH.js gzip	350 B	350 B	✓
hooks-HASH.js gzip	919 B	919 B	✓
image-HASH.js gzip	4.93 kB	4.94 kB	⚠️ +4 B
index-HASH.js gzip	263 B	263 B	✓
link-HASH.js gzip	2.19 kB	2.19 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	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	14.3 kB	14.4 kB	⚠️ +4 B

Client Build Manifests Overall decrease ✓

	vercel/next.js canary	Divlo/next.js fix/next-image-render-valid-html-w3c	Change
_buildManifest.js gzip	460 B	459 B	-1 B
Overall change	460 B	459 B	-1 B

Rendered Page Sizes

	vercel/next.js canary	Divlo/next.js fix/next-image-render-valid-html-w3c	Change
index.html gzip	530 B	530 B	✓
link.html gzip	545 B	545 B	✓
withRouter.html gzip	526 B	526 B	✓
Overall change	1.6 kB	1.6 kB	✓

Diffs

Diff for _buildManifest.js

@@ -12,7 +12,7 @@ self.__BUILD_MANIFEST = {
   ],
   "/head": ["static\u002Fchunks\u002Fpages\u002Fhead-7100d3b2a548f0e4.js"],
   "/hooks": ["static\u002Fchunks\u002Fpages\u002Fhooks-538d621a0e670391.js"],
-  "/image": ["static\u002Fchunks\u002Fpages\u002Fimage-2477effd702d0bcc.js"],
+  "/image": ["static\u002Fchunks\u002Fpages\u002Fimage-53463827ccaef972.js"],
   "/link": ["static\u002Fchunks\u002Fpages\u002Flink-f0a2c3bb0706d8b2.js"],
   "/routerDirect": [
     "static\u002Fchunks\u002Fpages\u002FrouterDirect-76232dd6bc335a24.js"

Diff for image-HASH.js

@@ -662,9 +662,8 @@
             wrapperStyle.maxWidth = "100%";
             hasSizer = true;
             sizerStyle.maxWidth = "100%";
-            // url encoded svg is a little bit shorten than base64 encoding
-            sizerSvgUrl = "data:image/svg+xml,%3csvg xmlns=%27http://www.w3.org/2000/svg%27 version=%271.1%27 width=%27"
-              .concat(widthInt, "%27 height=%27")
+            sizerSvgUrl = "data:image/svg+xml,%3csvg%20xmlns=%27http://www.w3.org/2000/svg%27%20version=%271.1%27%20width=%27"
+              .concat(widthInt, "%27%20height=%27")
               .concat(heightInt, "%27/%3e");
           } else if (layout === "fixed") {
             // <Image src="i.png" width="100" height="100" layout="fixed" />

Default Build with SWC (Decrease detected ✓)

General Overall decrease ✓

	vercel/next.js canary	Divlo/next.js fix/next-image-render-valid-html-w3c	Change
buildDuration	18.1s	18.2s	⚠️ +139ms
buildDurationCached	3.7s	3.7s	-34ms
nodeModulesSize	358 MB	358 MB	-95 B

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	Divlo/next.js fix/next-image-render-valid-html-w3c	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.443	3.394	-0.05
/ avg req/sec	726.13	736.52	+10.39
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.565	1.577	⚠️ +0.01
/error-in-render avg req/sec	1597.64	1585.09	⚠️ -12.55

Client Bundles (main, webpack, commons)

	vercel/next.js canary	Divlo/next.js fix/next-image-render-valid-html-w3c	Change
450.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.3 kB	42.3 kB	✓
main-HASH.js gzip	27.3 kB	27.3 kB	✓
webpack-HASH.js gzip	1.44 kB	1.44 kB	✓
Overall change	71.3 kB	71.3 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	Divlo/next.js fix/next-image-render-valid-html-w3c	Change
polyfills-HASH.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages Overall increase ⚠️

	vercel/next.js canary	Divlo/next.js fix/next-image-render-valid-html-w3c	Change
_app-HASH.js gzip	1.35 kB	1.35 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	2.36 kB	2.36 kB	✓
head-HASH.js gzip	342 B	342 B	✓
hooks-HASH.js gzip	911 B	911 B	✓
image-HASH.js gzip	4.97 kB	4.98 kB	⚠️ +5 B
index-HASH.js gzip	256 B	256 B	✓
link-HASH.js gzip	2.21 kB	2.21 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	✓
85e02e95b279..7e3.css gzip	107 B	107 B	✓
Overall change	14.3 kB	14.3 kB	⚠️ +5 B

Client Build Manifests

	vercel/next.js canary	Divlo/next.js fix/next-image-render-valid-html-w3c	Change
_buildManifest.js gzip	458 B	458 B	✓
Overall change	458 B	458 B	✓

Rendered Page Sizes

	vercel/next.js canary	Divlo/next.js fix/next-image-render-valid-html-w3c	Change
index.html gzip	531 B	531 B	✓
link.html gzip	544 B	544 B	✓
withRouter.html gzip	526 B	526 B	✓
Overall change	1.6 kB	1.6 kB	✓

Diffs

Diff for _buildManifest.js

@@ -12,7 +12,7 @@ self.__BUILD_MANIFEST = {
   ],
   "/head": ["static\u002Fchunks\u002Fpages\u002Fhead-7100d3b2a548f0e4.js"],
   "/hooks": ["static\u002Fchunks\u002Fpages\u002Fhooks-538d621a0e670391.js"],
-  "/image": ["static\u002Fchunks\u002Fpages\u002Fimage-2477effd702d0bcc.js"],
+  "/image": ["static\u002Fchunks\u002Fpages\u002Fimage-53463827ccaef972.js"],
   "/link": ["static\u002Fchunks\u002Fpages\u002Flink-f0a2c3bb0706d8b2.js"],
   "/routerDirect": [
     "static\u002Fchunks\u002Fpages\u002FrouterDirect-76232dd6bc335a24.js"

Diff for image-HASH.js

@@ -662,9 +662,8 @@
             wrapperStyle.maxWidth = "100%";
             hasSizer = true;
             sizerStyle.maxWidth = "100%";
-            // url encoded svg is a little bit shorten than base64 encoding
-            sizerSvgUrl = "data:image/svg+xml,%3csvg xmlns=%27http://www.w3.org/2000/svg%27 version=%271.1%27 width=%27"
-              .concat(widthInt, "%27 height=%27")
+            sizerSvgUrl = "data:image/svg+xml,%3csvg%20xmlns=%27http://www.w3.org/2000/svg%27%20version=%271.1%27%20width=%27"
+              .concat(widthInt, "%27%20height=%27")
               .concat(heightInt, "%27/%3e");
           } else if (layout === "fixed") {
             // <Image src="i.png" width="100" height="100" layout="fixed" />

Commit: 2a03501

theoludwig · 2022-02-01T09:42:01Z

I encoded space as %20 now it passes validation +1

Great, good solution! 👍 (better than reverting). Thanks for your help. @styfle

## Bug - [x] Fixes vercel#33809 - [x] Related to vercel#33218 - [x] Integration tests added: Usage of [html-validator](https://www.npmjs.com/package/html-validator) to validate the HTML. - [x] Errors have helpful link attached, see `contributing.md` (N/A)

theoludwig added 2 commits January 31, 2022 14:56

test(next/image): render valid HTML according to W3C

e4151df

fix(next/image): render valid HTML according to W3C

2fe8dac

theoludwig requested review from huozhi, ijjk, shuding, styfle and timneutkens as code owners January 31, 2022 13:59

ijjk added the type: next label Jan 31, 2022

theoludwig mentioned this pull request Jan 31, 2022

next/image produces invalid HTML according to W3C (again) #33809

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ijjk reviewed Jan 31, 2022

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theoludwig added 2 commits January 31, 2022 15:11

build(deps): bump html-validator from v6 to v5

0effe96

This allows to support Node.js v12 (ref: zrrrzzt/html-validator@c3a11fa)

refactor: move valid-html-w3c test to default

1aa3e6e

styfle reviewed Jan 31, 2022

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test/integration/image-component/default/test/index.test.js Outdated Show resolved Hide resolved

test: typo

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Co-authored-by: Steven <[email protected]>

styfle reviewed Jan 31, 2022

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theoludwig added 2 commits January 31, 2022 20:20

Revert "use text data url instead of base64 for shorter encoding (#33218

d0303d7

)" This reverts commit 628e6ac.

build(deps): usage of v5.1.18 instead of only v5 for html-validator

4e011b3

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Merge branch 'canary' into fix/next-image-render-valid-html-w3c

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styfle requested a review from sokra January 31, 2022 22:50

Replace space with %20

88caadb

styfle dismissed their stale review via 88caadb January 31, 2022 23:03

styfle added 2 commits January 31, 2022 18:03

Remove toBase64

a8e8a67

Merge branch 'canary' into fix/next-image-render-valid-html-w3c

2a03501

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styfle merged commit e0095fa into vercel:canary Feb 1, 2022

styfle mentioned this pull request Feb 1, 2022

cannot merge (missing required reviews) chdsbd/kodiak#784

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fix(next/image): render valid html according to W3C #33825

fix(next/image): render valid html according to W3C #33825

theoludwig commented Jan 31, 2022 •

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fix(next/image): render valid html according to W3C #33825

fix(next/image): render valid html according to W3C #33825

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Stats from current PR

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