fix: improve ssr template code generation (#10151)

* fix: improve ssr template code generation

* lint

.changeset/breezy-carrots-flash.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: improve ssr template code generation

packages/svelte/src/compiler/phases/3-transform/server/transform-server.js

@@ -187,10 +187,12 @@ function process_children(nodes, parent, { visit, state }) {
 			const node = sequence[i];
 			if (node.type === 'Text' || node.type === 'Comment') {
 				let last = /** @type {import('estree').TemplateElement} */ (quasis.at(-1));
-				last.value.raw +=
+				last.value.raw += node.type === 'Comment' ? `<!--${node.data}-->` : escape_html(node.data);
-					node.type === 'Comment'
+			} else if (node.type === 'ExpressionTag' && node.expression.type === 'Literal') {
-						? `<!--${node.data}-->`
+				let last = /** @type {import('estree').TemplateElement} */ (quasis.at(-1));
-						: sanitize_template_string(escape_html(node.data));
+				if (node.expression.value != null) {
+					last.value.raw += escape_html(node.expression.value + '');
+				}
 			} else if (node.type === 'Anchor') {
 				expressions.push(node.id);
 				quasis.push(b.quasi('', i + 1 === sequence.length));

packages/svelte/tests/snapshot/samples/each-string-template/_expected/server/index.svelte.js

@@ -14,7 +14,7 @@ export default function Each_string_template($$payload, $$props) {
 		const thing = each_array[$$index];
 		const anchor_1 = $.create_anchor($$payload);
 
-		$$payload.out += `${anchor_1}${$.escape(thing)},${$.escape(' ')}${anchor_1}`;
+		$$payload.out += `${anchor_1}${$.escape(thing)}, ${anchor_1}`;
 	}
 
 	$$payload.out += `${anchor}`;