From 4ca60e9344f882ee1a216ec66fb409c88c740641 Mon Sep 17 00:00:00 2001
From: Nate Moore <natemoo-re@users.noreply.github.com>
Date: Tue, 24 May 2022 14:39:23 -0500
Subject: [PATCH] Ensure hoisted scripts are deduplicated in build (#3433)

* fix(build): ensure hoisted scripts are deduplicated in build

* chore: add changeset
---
 .changeset/silly-ears-unite.md                |  5 ++++
 packages/astro/src/core/build/internal.ts     |  8 ++++++-
 packages/astro/src/core/build/static-build.ts | 23 +++++++++++++++++--
 .../core/build/vite-plugin-hoisted-scripts.ts | 15 ++++++------
 4 files changed, 41 insertions(+), 10 deletions(-)
 create mode 100644 .changeset/silly-ears-unite.md

diff --git a/.changeset/silly-ears-unite.md b/.changeset/silly-ears-unite.md
new file mode 100644
index 000000000000..b4e23917b4bf
--- /dev/null
+++ b/.changeset/silly-ears-unite.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fix build issue where hoisted scripts would be duplicated per page
diff --git a/packages/astro/src/core/build/internal.ts b/packages/astro/src/core/build/internal.ts
index c6f98a4fa5db..e796804fbb21 100644
--- a/packages/astro/src/core/build/internal.ts
+++ b/packages/astro/src/core/build/internal.ts
@@ -8,8 +8,10 @@ export interface BuildInternals {
 	// Pure CSS chunks are chunks that only contain CSS.
 	pureCSSChunks: Set<RenderedChunk>;
 
-	// TODO document what this is
+	// A mapping of hoisted script ids back to the exact hoisted scripts it references
 	hoistedScriptIdToHoistedMap: Map<string, Set<string>>;
+	// A mapping of hoisted script ids back to the pages which reference it
+	hoistedScriptIdToPagesMap: Map<string, Set<string>>;
 
 	// A mapping of specifiers like astro/client/idle.js to the hashed bundled name.
 	// Used to render pages with the correct specifiers.
@@ -50,9 +52,13 @@ export function createBuildInternals(): BuildInternals {
 	// These are for tracking hoisted script bundling
 	const hoistedScriptIdToHoistedMap = new Map<string, Set<string>>();
 
+	// This tracks hoistedScriptId => page components
+	const hoistedScriptIdToPagesMap = new Map<string, Set<string>>();
+
 	return {
 		pureCSSChunks,
 		hoistedScriptIdToHoistedMap,
+		hoistedScriptIdToPagesMap,
 		entrySpecifierToBundleMap: new Map<string, string>(),
 
 		pagesByComponent: new Map(),
diff --git a/packages/astro/src/core/build/static-build.ts b/packages/astro/src/core/build/static-build.ts
index ae08c54dc7d6..f101f6a3dc3f 100644
--- a/packages/astro/src/core/build/static-build.ts
+++ b/packages/astro/src/core/build/static-build.ts
@@ -38,6 +38,7 @@ export async function staticBuild(opts: StaticBuildOptions) {
 
 	// Build internals needed by the CSS plugin
 	const internals = createBuildInternals();
+	const uniqueHoistedIds = new Map<string, string>();
 
 	const timer: Record<string, number> = {};
 
@@ -76,9 +77,27 @@ export async function staticBuild(opts: StaticBuildOptions) {
 			// Add hoisted scripts
 			const hoistedScripts = new Set(metadata.hoistedScriptPaths());
 			if (hoistedScripts.size) {
-				const moduleId = npath.posix.join(astroModuleId, 'hoisted.js');
-				internals.hoistedScriptIdToHoistedMap.set(moduleId, hoistedScripts);
+				const uniqueHoistedId = JSON.stringify(Array.from(hoistedScripts).sort());
+				let moduleId: string;
+
+				// If we're already tracking this set of hoisted scripts, get the unique id
+				if (uniqueHoistedIds.has(uniqueHoistedId)) {
+					moduleId = uniqueHoistedIds.get(uniqueHoistedId)!;
+				} else {
+					// Otherwise, create a unique id for this set of hoisted scripts
+					moduleId = `/astro/hoisted.js?q=${uniqueHoistedIds.size}`;
+					uniqueHoistedIds.set(uniqueHoistedId, moduleId);
+				}
 				topLevelImports.add(moduleId);
+
+				// Make sure to track that this page uses this set of hoisted scripts
+				if (internals.hoistedScriptIdToPagesMap.has(moduleId)) {
+					const pages = internals.hoistedScriptIdToPagesMap.get(moduleId);
+					pages!.add(astroModuleId);
+				} else {
+					internals.hoistedScriptIdToPagesMap.set(moduleId, new Set([astroModuleId]))
+					internals.hoistedScriptIdToHoistedMap.set(moduleId, hoistedScripts);
+				}
 			}
 
 			for (const specifier of topLevelImports) {
diff --git a/packages/astro/src/core/build/vite-plugin-hoisted-scripts.ts b/packages/astro/src/core/build/vite-plugin-hoisted-scripts.ts
index 8e4872e0c7f1..4641b5f137ec 100644
--- a/packages/astro/src/core/build/vite-plugin-hoisted-scripts.ts
+++ b/packages/astro/src/core/build/vite-plugin-hoisted-scripts.ts
@@ -5,7 +5,7 @@ import { viteID } from '../util.js';
 import { getPageDataByViteID } from './internal.js';
 
 function virtualHoistedEntry(id: string) {
-	return id.endsWith('.astro/hoisted.js') || id.endsWith('.md/hoisted.js');
+	return id.startsWith('/astro/hoisted.js?q=');
 }
 
 export function vitePluginHoistedScripts(
@@ -49,12 +49,13 @@ export function vitePluginHoistedScripts(
 					virtualHoistedEntry(output.facadeModuleId)
 				) {
 					const facadeId = output.facadeModuleId!;
-					const pathname = facadeId.slice(0, facadeId.length - '/hoisted.js'.length);
-
-					const vid = viteID(new URL('.' + pathname, astroConfig.root));
-					const pageInfo = getPageDataByViteID(internals, vid);
-					if (pageInfo) {
-						pageInfo.hoistedScript = id;
+					const pages = internals.hoistedScriptIdToPagesMap.get(facadeId)!;
+					for (const pathname of pages) {
+						const vid = viteID(new URL('.' + pathname, astroConfig.root));
+						const pageInfo = getPageDataByViteID(internals, vid);
+						if (pageInfo) {
+							pageInfo.hoistedScript = id;
+						}
 					}
 				}
 			}