Add display: contents for hydrated components (#1794)

* Add display: contents for hydrated components

* Only serialize boolean attrs that are data attrs

* Adds a changeset

.changeset/dull-steaks-dance.md

@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Make astro-root be a display: contents element

packages/astro/src/runtime/server/hydration.ts

@@ -112,7 +112,7 @@ export async function generateHydrateScript(scriptOptions: HydrateScriptOptions,
 `;
 
   const hydrationScript = {
-    props: { type: 'module' },
+    props: { type: 'module', 'data-astro-component-hydration': true },
     children: `import setup from 'astro/client/${hydrate}.js';
 setup("${astroId}", {${metadata.hydrateArgs ? `value: ${JSON.stringify(metadata.hydrateArgs)}` : ''}}, async () => {
   ${hydrationSource}

packages/astro/src/runtime/server/index.ts

@@ -222,7 +222,12 @@ export function addAttribute(value: any, key: string) {
     return ` ${key.slice(0, -5)}="${toAttributeString(serializeListValue(value))}"`;
   }
 
-  return ` ${key}="${toAttributeString(value)}"`;
+  // Boolean only needs the key
+  if(value === true && key.startsWith('data-')) {
+    return ` ${key}`;
+  } else {
+    return ` ${key}="${toAttributeString(value)}"`;
+  }
 }
 
 // Adds support for `<Component {...value} />
@@ -278,14 +283,21 @@ export async function renderPage(result: SSRResult, Component: AstroComponentFac
         props: { ...style.props, 'astro-style': true },
       })
     );
+  let needsHydrationStyles = false;
   const scripts = Array.from(result.scripts)
     .filter(uniqueElements)
-    .map((script, i) =>
-      renderElement('script', {
+    .map((script, i) => {
+      if('data-astro-component-hydration' in script.props) {
+        needsHydrationStyles = true;
+      }
+      return renderElement('script', {
         ...script,
         props: { ...script.props, 'astro-script': result._metadata.pathname + '/script-' + i },
-      })
-    );
+      });
+    });
+  if(needsHydrationStyles) {
+    styles.push(renderElement('style', { props: { 'astro-style': true },children: 'astro-root, astro-fragment { display: contents; }' }))
+  }
   return template.replace('</head>', styles.join('\n') + scripts.join('\n') + '</head>');
 }
 

packages/astro/src/vite-plugin-build-html/index.ts

@@ -7,7 +7,7 @@ import parse5 from 'parse5';
 import srcsetParse from 'srcset-parse';
 import * as npath from 'path';
 import { promises as fs } from 'fs';
-import { getAttribute, getTagName, insertBefore, remove, createScript, createElement, setAttribute } from '@web/parse5-utils';
+import { getAttribute, hasAttribute, getTagName, insertBefore, remove, createScript, createElement, setAttribute } from '@web/parse5-utils';
 import { addRollupInput } from './add-rollup-input.js';
 import { findAssets, findInlineScripts, findInlineStyles, getTextContent, isStylesheetLink } from './extract-assets.js';
 import { render as ssrRender } from '../core/ssr/index.js';
@@ -109,7 +109,7 @@ export function rollupPluginAstroBuildHTML(options: PluginOptions): VitePlugin {
 
           let styles = '';
           for (const node of findInlineStyles(document)) {
-            if (getAttribute(node, 'astro-style')) {
+            if (hasAttribute(node, 'astro-style')) {
               styles += getTextContent(node);
             }
           }
@@ -374,7 +374,7 @@ export function rollupPluginAstroBuildHTML(options: PluginOptions): VitePlugin {
 
         // Page styles for <style> usage, if not already appended via links.
         for (const style of findInlineStyles(document)) {
-          if (getAttribute(style, 'astro-style')) {
+          if (hasAttribute(style, 'astro-style')) {
             if (!pageCSSAdded) {
               pageCSSAdded = appendStyleChunksBefore(style, pathname, cssChunkMap.get(styleId));
             }

packages/astro/test/astro-styles-ssr.test.js

@@ -125,4 +125,13 @@ describe('Styles SSR', () => {
 
     expect($('#passed-in').attr('class')).to.match(/outer astro-[A-Z0-9]+ astro-[A-Z0-9]+/);
   });
+
+  it('Using hydrated components adds astro-root styles', async () => {
+    const html = await fixture.readFile('/index.html');
+    const $ = cheerio.load(html);
+
+    const href = '/' + $('link').attr('href');
+    const css = await fixture.readFile(href);
+    expect(css).to.include('display: contents;');
+  });
 });

packages/astro/test/fixtures/astro-styles-ssr/src/components/ReactDynamic.jsx

@@ -0,0 +1,5 @@
+import React from 'react';
+
+export default function() {
+  return <div></div>;
+}

packages/astro/test/fixtures/astro-styles-ssr/src/pages/index.astro

@@ -7,6 +7,7 @@ import VueCSS from '../components/VueCSS.vue';
 import VueScoped from '../components/VueScoped.vue';
 import VueModules from '../components/VueModules.vue';
 import SvelteScoped from '../components/SvelteScoped.svelte';
+import ReactDynamic from '../components/ReactDynamic.jsx';
 ---
 
 <html>
@@ -33,6 +34,7 @@ import SvelteScoped from '../components/SvelteScoped.svelte';
       <VueScoped />
       <VueModules />
       <SvelteScoped />
+      <ReactDynamic client:load />
     </div>
   </body>
 </html>