use helpers

src/compiler/compile/render-ssr/handlers/Element.ts

@@ -162,12 +162,12 @@ export default function(node: Element, renderer: Renderer, options: RenderOption
 			node_contents = '${(' + snippet + ') || ""}';
 		} else {
 			const snippet = snip(expression);
-			opening_tag += ' ${($$value => $$value ? ("' + name + '" + ($$value === true ? "" : "=" + JSON.stringify($$value))) : "")(' + snippet + ')}';
+			opening_tag += '${@add_attribute("' + name + '", ' + snippet + ')}';
 		}
 	});
 
 	if (add_class_attribute) {
-		opening_tag += `\${(($$value) => $$value ? ' class="' + $$value + '"' : '')([${class_expression}].join(' ').trim())}`;
+		opening_tag += `\${@add_classes([${class_expression}].join(' ').trim())}`;
 	}
 
 	opening_tag += '>';

src/runtime/internal/ssr.ts

@@ -118,4 +118,13 @@ export function get_store_value<T>(store: Readable<T>): T | undefined {
 	let value;
 	store.subscribe(_ => value = _)();
 	return value;
+}
+
+export function add_attribute(name, value) {
+	if (!value) return '';
+	return ` ${name}${value === true ? '' : `=${JSON.stringify(value)}`}`;
+}
+
+export function add_classes(classes) {
+	return classes ? ` class="${classes}"` : ``;
 }