improve performance of render_ssr

src/compiler/compile/render_ssr/handlers/Element.ts

@@ -24,7 +24,7 @@ export default function (node: Element, renderer: Renderer, options: RenderOptio
 	);
 
 	renderer.add_string('<');
-	renderer.add_expression(node.tag_expr.node as ESExpression);
+	add_tag_name();
 
 	const class_expression_list = node.classes.map(class_directive => {
 		const { expression, name } = class_directive;
@@ -162,9 +162,17 @@ export default function (node: Element, renderer: Renderer, options: RenderOptio
 	function add_close_tag() {
 		if (!is_void(node.name)) {
 			renderer.add_string('</');
-			renderer.add_expression(node.tag_expr.node as ESExpression);
+			add_tag_name();
 			renderer.add_string('>');
 		}
 	}
+
+	function add_tag_name() {
+		if (node.tag_expr.node.type === 'Literal') {
+			renderer.add_string(node.tag_expr.node.value as string);
+		} else {
+			renderer.add_expression(node.tag_expr.node as ESExpression);
+		}
+	}
 }
 

test/js/samples/debug-ssr-foo/expected.js

@@ -7,10 +7,10 @@ const Component = create_ssr_component(($$result, $$props, $$bindings, slots) =>
 	if ($$props.things === void 0 && $$bindings.things && things !== void 0) $$bindings.things(things);
 	if ($$props.foo === void 0 && $$bindings.foo && foo !== void 0) $$bindings.foo(foo);
 
-	return `${each(things, thing => `<${"span"}>${escape(thing.name)}</${"span"}>
+	return `${each(things, thing => `<span>${escape(thing.name)}</span>
 	${debug(null, 7, 2, { foo })}`)}
 
-<${"p"}>foo: ${escape(foo)}</${"p"}>`;
+<p>foo: ${escape(foo)}</p>`;
 });
 
 export default Component;

test/js/samples/ssr-preserve-comments/expected.js

@@ -2,9 +2,9 @@
 import { create_ssr_component } from "svelte/internal";
 
 const Component = create_ssr_component(($$result, $$props, $$bindings, slots) => {
-	return `<${"div"}>content</${"div"}>
+	return `<div>content</div>
 <!-- comment -->
-<${"div"}>more content</${"div"}>`;
+<div>more content</div>`;
 });
 
 export default Component;