From e78cfd393e16fb754f7393b535d2120815010381 Mon Sep 17 00:00:00 2001
From: Dominic Gannaway <trueadm@users.noreply.github.com>
Date: Mon, 5 Aug 2024 17:03:27 +0100
Subject: [PATCH] fix: correctly handle SvelteDate methods with arguments
 (#12738)

* fix: correctly handle SvelteDate methods with arguments

* tweak

* Update packages/svelte/src/reactivity/date.js

* Update packages/svelte/src/reactivity/date.js

Co-authored-by: Rich Harris <rich.harris@vercel.com>

* Update packages/svelte/src/reactivity/date.test.ts

---------

Co-authored-by: Rich Harris <rich.harris@vercel.com>
---
 .changeset/dirty-pens-look.md               |  5 +++++
 packages/svelte/src/reactivity/date.js      |  8 +++++++
 packages/svelte/src/reactivity/date.test.ts | 24 +++++++++++++++++++++
 3 files changed, 37 insertions(+)
 create mode 100644 .changeset/dirty-pens-look.md

diff --git a/.changeset/dirty-pens-look.md b/.changeset/dirty-pens-look.md
new file mode 100644
index 0000000000..16536edce7
--- /dev/null
+++ b/.changeset/dirty-pens-look.md
@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: correctly handle SvelteDate methods with arguments
diff --git a/packages/svelte/src/reactivity/date.js b/packages/svelte/src/reactivity/date.js
index 1b64097e73..a1fb73c5f5 100644
--- a/packages/svelte/src/reactivity/date.js
+++ b/packages/svelte/src/reactivity/date.js
@@ -32,6 +32,14 @@ export class SvelteDate extends Date {
 			if (method.startsWith('get') || method.startsWith('to')) {
 				// @ts-ignore
 				proto[method] = function (...args) {
+					// don't memoize if there are arguments
+					// @ts-ignore
+					if (args.length > 0) {
+						get(this.#time);
+						// @ts-ignore
+						return date_proto[method].apply(this, args);
+					}
+
 					var d = this.#deriveds.get(method);
 
 					if (d === undefined) {
diff --git a/packages/svelte/src/reactivity/date.test.ts b/packages/svelte/src/reactivity/date.test.ts
index d1732d26b1..e2702d9ff6 100644
--- a/packages/svelte/src/reactivity/date.test.ts
+++ b/packages/svelte/src/reactivity/date.test.ts
@@ -555,6 +555,30 @@ test('Date fine grained tests', () => {
 	cleanup();
 });
 
+test('Date.toLocaleString', () => {
+	const date = new SvelteDate(initial_date);
+
+	const log: any = [];
+
+	const cleanup = effect_root(() => {
+		render_effect(() => {
+			log.push(date.toLocaleString(undefined, { month: 'long', year: 'numeric' }));
+		});
+		render_effect(() => {
+			log.push(date.toLocaleString(undefined, { month: 'long' }));
+		});
+	});
+
+	flushSync();
+
+	assert.deepEqual(log, [
+		initial_date.toLocaleString(undefined, { month: 'long', year: 'numeric' }),
+		initial_date.toLocaleString(undefined, { month: 'long' })
+	]);
+
+	cleanup();
+});
+
 test('Date.instanceOf', () => {
 	assert.equal(new SvelteDate() instanceof Date, true);
 });