core(tags-blocking-first-paint): ignore malformed link tags (#15489)

GoogleChrome · Sep 21, 2023 · aa8d489 · aa8d489
1 parent 7d46afa
commit aa8d489
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diff --git a/cli/test/fixtures/dobetterweb/dbw_tester.html b/cli/test/fixtures/dobetterweb/dbw_tester.html
@@ -45,6 +45,9 @@
 <!-- Alternate stylesheets should not show in TagsBlockingFirstPaint artifact -->
 <link rel="alternate stylesheet" href="./empty.css">
 
+<!-- Malformed links should not show in TagsBlockingFirstPaint artifact -->
+<link rel="stylesheet" href="">
+
 <!-- FAIL: block rendering -->
 <script src="./dbw_tester.js" id="dbw-tester-script"></script>
 

diff --git a/cli/test/smokehouse/test-definitions/dobetterweb.js b/cli/test/smokehouse/test-definitions/dobetterweb.js
@@ -121,6 +121,15 @@ const expectations = {
         crossOrigin: null,
         source: 'head',
       },
+      {
+        rel: 'stylesheet',
+        href: 'http://localhost:10200/dobetterweb/dbw_tester.html',
+        hrefRaw: '',
+        hreflang: '',
+        as: '',
+        crossOrigin: null,
+        source: 'head',
+      },
       {
         rel: 'stylesheet',
         href: 'http://localhost:10200/dobetterweb/dbw_tester.css?scriptActivated&delay=200',

diff --git a/core/gather/gatherers/dobetterweb/tags-blocking-first-paint.js b/core/gather/gatherers/dobetterweb/tags-blocking-first-paint.js
@@ -62,6 +62,11 @@ async function collectTagsThatBlockFirstPaint() {
     /** @type {Array<LinkTag>} */
     const linkTags = [...document.querySelectorAll('link')]
       .filter(linkTag => {
+        // Ignore malformed links with no href (e.g. `<link rel="stylesheet" href="">`)
+        // The resolved `linkTag.href` will be the main document, but the main document
+        // should never be render blocking.
+        if (!linkTag.getAttribute('href')) return false;
+
         // Filter stylesheet/HTML imports that block rendering.
         // https://www.igvita.com/2012/06/14/debunking-responsive-css-performance-myths/
         // https://www.w3.org/TR/html-imports/#dfn-import-async-attribute