From 0aa1abc70f95d191424853ddbb4512e0880adb34 Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Sat, 25 Nov 2023 16:26:00 -0500
Subject: [PATCH] WIP

---
 .../compiler/phases/1-parse/read/options.js    |  3 ++-
 .../3-transform/client/visitors/template.js    |  4 +---
 packages/svelte/src/constants.js               |  3 +++
 packages/svelte/src/internal/client/render.js  | 18 +++++++++++-------
 4 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/packages/svelte/src/compiler/phases/1-parse/read/options.js b/packages/svelte/src/compiler/phases/1-parse/read/options.js
index 31e81c7c71..69ca025f58 100644
--- a/packages/svelte/src/compiler/phases/1-parse/read/options.js
+++ b/packages/svelte/src/compiler/phases/1-parse/read/options.js
@@ -1,3 +1,4 @@
+import { namespace_svg } from '../../../../constants.js';
 import { error } from '../../../errors.js';
 
 const regex_valid_tag_name = /^[a-zA-Z][a-zA-Z0-9]*-[a-zA-Z0-9-]+$/;
@@ -156,7 +157,7 @@ export default function read_options(node) {
 					error(attribute, 'invalid-svelte-option-namespace');
 				}
 
-				if (value === 'http://www.w3.org/2000/svg') {
+				if (value === namespace_svg) {
 					component_options.namespace = 'svg';
 				} else if (value === 'html' || value === 'svg' || value === 'foreign') {
 					component_options.namespace = value;
diff --git a/packages/svelte/src/compiler/phases/3-transform/client/visitors/template.js b/packages/svelte/src/compiler/phases/3-transform/client/visitors/template.js
index b5b58c34dc..36deebaa14 100644
--- a/packages/svelte/src/compiler/phases/3-transform/client/visitors/template.js
+++ b/packages/svelte/src/compiler/phases/3-transform/client/visitors/template.js
@@ -2102,9 +2102,7 @@ export const template_visitors = {
 					context.state.node,
 					get_tag,
 					b.arrow([element_id, b.id('$$anchor')], b.block(inner)),
-					namespace === 'http://www.w3.org/2000/svg'
-						? b.literal(true)
-						: /** @type {any} */ (undefined)
+					namespace ? b.literal(namespace) : /** @type {any} */ (undefined)
 				)
 			)
 		);
diff --git a/packages/svelte/src/constants.js b/packages/svelte/src/constants.js
index a8abda2237..e0f24859dd 100644
--- a/packages/svelte/src/constants.js
+++ b/packages/svelte/src/constants.js
@@ -77,3 +77,6 @@ export const DOMBooleanAttributes = [
 	'seamless',
 	'selected'
 ];
+
+export const namespace_svg = 'http://www.w3.org/2000/svg';
+export const namespace_html = 'http://www.w3.org/1999/xhtml';
diff --git a/packages/svelte/src/internal/client/render.js b/packages/svelte/src/internal/client/render.js
index afb060639a..647afc58ff 100644
--- a/packages/svelte/src/internal/client/render.js
+++ b/packages/svelte/src/internal/client/render.js
@@ -28,7 +28,9 @@ import {
 	EACH_ITEM_REACTIVE,
 	PassiveDelegatedEvents,
 	DelegatedEvents,
-	AttributeAliases
+	AttributeAliases,
+	namespace_svg,
+	namespace_html
 } from '../../constants.js';
 import {
 	create_fragment_from_html,
@@ -1543,10 +1545,10 @@ function swap_block_dom(block, from, to) {
  * @param {Comment} anchor_node
  * @param {() => string} tag_fn
  * @param {null | ((element: Element, anchor: Node) => void)} render_fn
- * @param {any} is_svg
+ * @param {string} namespace
  * @returns {void}
  */
-export function element(anchor_node, tag_fn, render_fn, is_svg = false) {
+export function element(anchor_node, tag_fn, render_fn, namespace) {
 	const block = create_dynamic_element_block();
 	hydrate_block_anchor(anchor_node);
 	let has_mounted = false;
@@ -1570,11 +1572,13 @@ export function element(anchor_node, tag_fn, render_fn, is_svg = false) {
 	// Managed effect
 	const render_effect_signal = render_effect(
 		() => {
+			const ns = namespace ?? tag === 'svg' ? namespace_svg : null;
+			console.log(anchor_node);
 			const next_element = tag
 				? current_hydration_fragment !== null
 					? /** @type {HTMLElement | SVGElement} */ (current_hydration_fragment[0])
-					: is_svg
-					? document.createElementNS('http://www.w3.org/2000/svg', tag)
+					: ns
+					? document.createElementNS(ns, tag)
 					: document.createElement(tag)
 				: null;
 			const prev_element = element;
@@ -2327,7 +2331,7 @@ export function cssProps(anchor, is_html, props, component) {
 			tag = document.createElement('div');
 			tag.style.display = 'contents';
 		} else {
-			tag = document.createElementNS('http://www.w3.org/2000/svg', 'g');
+			tag = document.createElementNS(namespace_svg, 'g');
 		}
 		insert(tag, null, anchor);
 		component_anchor = empty();
@@ -2821,7 +2825,7 @@ export function spread_dynamic_element_attributes(node, prev, attrs, css_hash) {
 			/** @type {Element & ElementCSSInlineStyle} */ (node),
 			prev,
 			attrs,
-			node.namespaceURI !== 'http://www.w3.org/2000/svg',
+			node.namespaceURI !== namespace_svg,
 			css_hash
 		);
 	}