fix: ensure SVG element attributes have case preserved

Author: trueadm

.changeset/gentle-bulldogs-cough.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: ensure SVG element attributes have case preserved

packages/svelte/src/compiler/phases/3-transform/client/visitors/SvelteElement.js

@@ -101,7 +101,7 @@ export function SvelteElement(node, context) {
 			node,
 			element_id,
 			attributes_id,
-			b.binary('!==', b.member(element_id, 'namespaceURI'), b.id('$.NAMESPACE_SVG')),
+			b.binary('===', b.member(element_id, 'namespaceURI'), b.id('$.NAMESPACE_SVG')),
 			b.call(b.member(b.member(element_id, 'nodeName'), 'includes'), b.literal('-')),
 			context.state
 		);

packages/svelte/src/internal/client/dom/elements/attributes.js

@@ -170,6 +170,7 @@ export function set_attributes(
 	var current = prev || {};
 	var is_option_element = element.tagName === 'OPTION';
 
+
 	for (var key in prev) {
 		if (!(key in next)) {
 			next[key] = null;

packages/svelte/tests/runtime-runes/samples/svg-attribute-case/_config.js

@@ -0,0 +1,5 @@
+import { test } from '../../test';
+
+export default test({
+	html: `<svg viewBox="0 0 10 10"></svg><svg viewBox="0 0 10 10" xmlns="http://www.w3.org/2000/svg"></svg><svg viewBox=""></svg`
+});

packages/svelte/tests/runtime-runes/samples/svg-attribute-case/main.svelte

@@ -0,0 +1,4 @@
+<svelte:options namespace="svg" />
+<svelte:element this="svg" viewBox="0 0 10 10" />
+<svelte:element this="svg" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 10 10" />
+<svg viewBox="" />