From ce7845cbcfea41b63e93feab6c67a06ce654a912 Mon Sep 17 00:00:00 2001
From: Julien Huang <julien.huang@outlook.fr>
Date: Thu, 18 Jan 2024 23:20:01 +0100
Subject: [PATCH] fix(nuxt): allow omitting `fallback` in island response
 (#25296)

---
 packages/nuxt/src/app/components/nuxt-island.ts  | 2 +-
 packages/nuxt/src/core/runtime/nitro/renderer.ts | 4 ++--
 test/basic.test.ts                               | 2 --
 3 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/packages/nuxt/src/app/components/nuxt-island.ts b/packages/nuxt/src/app/components/nuxt-island.ts
index 4d9c27b54c..9457099918 100644
--- a/packages/nuxt/src/app/components/nuxt-island.ts
+++ b/packages/nuxt/src/app/components/nuxt-island.ts
@@ -134,7 +134,7 @@ export default defineComponent({
 
       return html.replaceAll(SLOT_FALLBACK_RE, (full, slotName) => {
         if (!currentSlots.includes(slotName)) {
-          return full + payloadSlots[slotName]?.fallback ?? ''
+          return full + (payloadSlots[slotName]?.fallback || '')
         }
         return full
       })
diff --git a/packages/nuxt/src/core/runtime/nitro/renderer.ts b/packages/nuxt/src/core/runtime/nitro/renderer.ts
index b1e4c20fda..964f76272c 100644
--- a/packages/nuxt/src/core/runtime/nitro/renderer.ts
+++ b/packages/nuxt/src/core/runtime/nitro/renderer.ts
@@ -64,7 +64,7 @@ export interface NuxtIslandContext {
 
 export interface NuxtIslandSlotResponse {
   props: Array<unknown>
-  fallback: string
+  fallback?: string
 }
 export interface NuxtIslandClientResponse {
   html: string
@@ -626,7 +626,7 @@ function getSlotIslandResponse (ssrContext: NuxtSSRContext): NuxtIslandResponse[
   for (const slot in ssrContext.islandContext.slots) {
     response[slot] = {
       ...ssrContext.islandContext.slots[slot],
-      fallback: ssrContext.teleports?.[`island-fallback=${slot}`] || ''
+      fallback: ssrContext.teleports?.[`island-fallback=${slot}`]
     }
   }
   return response
diff --git a/test/basic.test.ts b/test/basic.test.ts
index ab67992c8c..5294cbf7c0 100644
--- a/test/basic.test.ts
+++ b/test/basic.test.ts
@@ -1825,7 +1825,6 @@ describe('component islands', () => {
         "html": "<div data-island-uid><div> count is above 2 </div><!--[--><div style="display: contents;" data-island-uid data-island-slot="default"></div><!--]--> that was very long ... <div id="long-async-component-count">3</div>  <!--[--><div style="display: contents;" data-island-uid data-island-slot="test"></div><!--]--><p>hello world !!!</p><!--[--><div style="display: contents;" data-island-uid data-island-slot="hello"></div><!--teleport start--><!--teleport end--><!--]--><!--[--><div style="display: contents;" data-island-uid data-island-slot="fallback"></div><!--teleport start--><!--teleport end--><!--]--></div>",
         "slots": {
           "default": {
-            "fallback": "",
             "props": [],
           },
           "fallback": {
@@ -1854,7 +1853,6 @@ describe('component islands', () => {
             ],
           },
           "test": {
-            "fallback": "",
             "props": [
               {
                 "count": 3,