add languages.current to reactivity/window

.changeset/shy-tomatoes-relate.md

@@ -0,0 +1,5 @@
+---
+'svelte': minor
+---
+
+add languages.current to svelte/reactivity/window

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)
+);

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><!--]-->
+<!--[--><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><!--]-->

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>

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);