From 17278c9715d4281633237b9c834461d9c05b5ff0 Mon Sep 17 00:00:00 2001
From: iainb <ibroadfo@local>
Date: Fri, 2 May 2025 11:19:15 +0100
Subject: [PATCH] add languages.current to reactivity/window

---
 .changeset/shy-tomatoes-relate.md                        | 5 +++++
 packages/svelte/src/reactivity/window/index.js           | 9 +++++++++
 .../samples/reactivity-window/_expected.html             | 2 +-
 .../samples/reactivity-window/main.svelte                | 3 ++-
 packages/svelte/types/index.d.ts                         | 4 ++++
 5 files changed, 21 insertions(+), 2 deletions(-)
 create mode 100644 .changeset/shy-tomatoes-relate.md

diff --git a/.changeset/shy-tomatoes-relate.md b/.changeset/shy-tomatoes-relate.md
new file mode 100644
index 0000000000..4274592e37
--- /dev/null
+++ b/.changeset/shy-tomatoes-relate.md
@@ -0,0 +1,5 @@
+---
+'svelte': minor
+---
+
+add languages.current to svelte/reactivity/window
diff --git a/packages/svelte/src/reactivity/window/index.js b/packages/svelte/src/reactivity/window/index.js
index 8c50a5c440..4ccae39d1f 100644
--- a/packages/svelte/src/reactivity/window/index.js
+++ b/packages/svelte/src/reactivity/window/index.js
@@ -154,3 +154,12 @@ export const devicePixelRatio = /* @__PURE__ */ new (class DevicePixelRatio {
 		return BROWSER ? window.devicePixelRatio : undefined;
 	}
 })();
+
+/**
+ * `languages.current` is a reactive view of `navigator.languages`. On the server it is `undefined`.
+ * @since
+ */
+export const languages = new ReactiveValue(
+	BROWSER ? () => navigator.languages : () => undefined,
+	(update) => on(window, 'languagechange', update)
+);
diff --git a/packages/svelte/tests/server-side-rendering/samples/reactivity-window/_expected.html b/packages/svelte/tests/server-side-rendering/samples/reactivity-window/_expected.html
index ee65cb76c7..09d272c511 100644
--- a/packages/svelte/tests/server-side-rendering/samples/reactivity-window/_expected.html
+++ b/packages/svelte/tests/server-side-rendering/samples/reactivity-window/_expected.html
@@ -1 +1 @@
-<!--[--><p>devicePixelRatio: </p> <p>innerHeight: </p> <p>innerWidth: </p> <p>online: </p> <p>outerHeight: </p> <p>outerWidth: </p> <p>screenLeft: </p> <p>screenTop: </p> <p>scrollX: </p> <p>scrollY: </p><!--]-->
\ No newline at end of file
+<!--[--><p>devicePixelRatio: </p> <p>innerHeight: </p> <p>innerWidth: </p> <p>languages: </p> <p>online: </p> <p>outerHeight: </p> <p>outerWidth: </p> <p>screenLeft: </p> <p>screenTop: </p> <p>scrollX: </p> <p>scrollY: </p><!--]-->
\ No newline at end of file
diff --git a/packages/svelte/tests/server-side-rendering/samples/reactivity-window/main.svelte b/packages/svelte/tests/server-side-rendering/samples/reactivity-window/main.svelte
index e84e41bf63..8b9f37aa4c 100644
--- a/packages/svelte/tests/server-side-rendering/samples/reactivity-window/main.svelte
+++ b/packages/svelte/tests/server-side-rendering/samples/reactivity-window/main.svelte
@@ -1,10 +1,11 @@
 <script>
-	import { devicePixelRatio, innerHeight, innerWidth, online, outerHeight, outerWidth, screenLeft, screenTop, scrollX, scrollY } from "svelte/reactivity/window";
+	import { devicePixelRatio, innerHeight, innerWidth, languages, online, outerHeight, outerWidth, screenLeft, screenTop, scrollX, scrollY } from "svelte/reactivity/window";
 </script>
 
 <p>devicePixelRatio: {devicePixelRatio.current}</p>
 <p>innerHeight: {innerHeight.current}</p>
 <p>innerWidth: {innerWidth.current}</p>
+<p>languages: {languages.current}</p>
 <p>online: {online.current}</p>
 <p>outerHeight: {outerHeight.current}</p>
 <p>outerWidth: {outerWidth.current}</p>
diff --git a/packages/svelte/types/index.d.ts b/packages/svelte/types/index.d.ts
index b233cfcc0b..b763a46198 100644
--- a/packages/svelte/types/index.d.ts
+++ b/packages/svelte/types/index.d.ts
@@ -2224,6 +2224,10 @@ declare module 'svelte/reactivity/window' {
 	export const devicePixelRatio: {
 		get current(): number | undefined;
 	};
+	/**
+	 * `languages.current` is a reactive view of `navigator.languages`. On the server it is `undefined`.
+	 * */
+	export const languages: ReactiveValue<readonly string[] | undefined>;
 	class ReactiveValue<T> {
 		
 		constructor(fn: () => T, onsubscribe: (update: () => void) => void);