Repair server islands to work with client router (#13481)

* rerun server island scripts when used with client router

2 files changed, 11 insertions, 6 deletions

diff --git a/.changeset/tough-tires-kneel.md b/.changeset/tough-tires-kneel.md
new file mode 100644
index 000000000..61d5afcad
--- /dev/null
+++ b/.changeset/tough-tires-kneel.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Makes server island work with the client router again.
diff --git a/packages/astro/src/runtime/server/render/server-islands.ts b/packages/astro/src/runtime/server/render/server-islands.ts
index 093254cd3..05617a7f6 100644
--- a/packages/astro/src/runtime/server/render/server-islands.ts
+++ b/packages/astro/src/runtime/server/render/server-islands.ts
@@ -105,7 +105,7 @@ export function renderServerIsland(
 				);
 			}
 
-			destination.write(`<script async type="module" data-island-id="${hostId}">
+			destination.write(`<script async type="module" data-astro-rerun data-island-id="${hostId}">
 let script = document.querySelector('script[data-island-id="${hostId}"]');
 
 ${
@@ -128,11 +128,11 @@ let response = await fetch('${serverIslandUrl}', {
 }
 if (script) {
 	if(
-		response.status === 200 
-		&& response.headers.has('content-type') 
+		response.status === 200
+		&& response.headers.has('content-type')
 		&& response.headers.get('content-type').split(";")[0].trim() === 'text/html') {
 		let html = await response.text();
-	
+
 		// Swap!
 		while(script.previousSibling &&
 			script.previousSibling.nodeType !== 8 &&
@@ -140,11 +140,11 @@ if (script) {
 			script.previousSibling.remove();
 		}
 		script.previousSibling?.remove();
-	
+
 		let frag = document.createRange().createContextualFragment(html);
 		script.before(frag);
 	}
-	script.remove();
+	script.remove(); // Prior to v5.4.2, this was the trick to force rerun of scripts.  Keeping it to minimize change to the existing behavior.
 }
 </script>`);
 		},