skip definition if unnecessary

src/compile/Component.ts

@@ -51,6 +51,7 @@ export default class Component {
 
 	ast: Ast;
 	source: string;
+	code: MagicString;
 	name: string;
 	options: CompileOptions;
 	fragment: Fragment;
@@ -77,8 +78,7 @@ export default class Component {
 	module_exports: Array<{ name: string, as: string }> = [];
 	partly_hoisted: string[] = [];
 	fully_hoisted: string[] = [];
-
-	code: MagicString;
+	has_reactive_assignments = false;
 
 	indirectDependencies: Map<string, Set<string>> = new Map();
 	template_references: Set<string> = new Set();
@@ -663,6 +663,8 @@ export default class Component {
 		else {
 			this.code.appendLeft(node.end, `; $$make_dirty('${name}')`);
 		}
+
+		this.has_reactive_assignments = true;
 	}
 }
 

src/compile/nodes/shared/Expression.ts

@@ -239,8 +239,6 @@ export default class Expression {
 						// TODO handle destructuring assignments
 						const { name } = flattenReference(node.left);
 						pending_assignments.add(name);
-
-						// code.appendLeft(node.end, `; $$make_dirty('${name}')`);
 					}
 				} else {
 					if (node.type === 'AssignmentExpression') {
@@ -290,6 +288,8 @@ export default class Expression {
 							const insert = [...pending_assignments].map(name => `$$make_dirty('${name}');`);
 							pending_assignments = new Set();
 
+							component.has_reactive_assignments = true;
+
 							body = deindent`
 								{
 									const $$result = ${body};

src/compile/render-dom/index.ts

@@ -168,6 +168,10 @@ export default function dom(
 		});
 	}
 
+	const args = ['$$self'];
+	if (component.props.length > 0 || component.has_reactive_assignments) args.push('$$props');
+	if (component.has_reactive_assignments) args.push('$$make_dirty');
+
 	builder.addBlock(deindent`
 		function create_fragment(${component.alias('component')}, ctx) {
 			${block.getContents()}
@@ -176,8 +180,22 @@ export default function dom(
 		${component.module_javascript}
 
 		${component.fully_hoisted.length > 0 && component.fully_hoisted.join('\n\n')}
+	`);
+
+	let has_definition = (
+		component.javascript ||
+		component.props.length > 0 ||
+		component.partly_hoisted.length > 0 ||
+		component.declarations.length > 0
+	);
 
-		function ${component.alias('define')}($$self, $$props, $$make_dirty) {
+	const definition = has_definition
+		? component.alias('define')
+		: '@noop';
+
+	if (has_definition) {
+		builder.addBlock(deindent`
+			function ${definition}(${args.join(', ')}) {
 				${component.javascript || (
 					component.props.length > 0 &&
 					`let { ${component.props.map(x => x.name === x.as ? x.as : `${x.as}: ${x.name}`).join(', ')} } = $$props;`
@@ -192,6 +210,7 @@ export default function dom(
 				${inject_refs && `$$self.$$.inject_refs = ${inject_refs};`}
 			}
 		`);
+	}
 
 	if (options.customElement) {
 		builder.addBlock(deindent`
@@ -201,7 +220,7 @@ export default function dom(
 
 					${css.code && `this.shadowRoot.innerHTML = \`<style>${escape(css.code, { onlyEscapeAtSymbol: true }).replace(/\\/g, '\\\\')}${options.dev ? `\n/*# sourceMappingURL=${css.map.toUrl()} */` : ''}</style>\`;`}
 
-					@init(this, { target: this.shadowRoot }, ${component.alias('define')}, create_fragment, ${not_equal});
+					@init(this, { target: this.shadowRoot }, ${definition}, create_fragment, ${not_equal});
 
 					${dev_props_check}
 
@@ -221,7 +240,7 @@ export default function dom(
 					return ${JSON.stringify(component.props.map(x => x.as))};
 				}
 
-				${body.join('\n\n')}
+				${body.length > 0 && body.join('\n\n')}
 			}
 
 			customElements.define("${component.tag}", ${name});
@@ -232,12 +251,12 @@ export default function dom(
 				constructor(options) {
 					super(${options.dev && `options`});
 					${should_add_css && `if (!document.getElementById("${component.stylesheet.id}-style")) @add_css();`}
-					@init(this, options, define, create_fragment, ${not_equal});
+					@init(this, options, ${definition}, create_fragment, ${not_equal});
 
 					${dev_props_check}
 				}
 
-				${body.join('\n\n')}
+				${body.length > 0 && body.join('\n\n')}
 			}
 		`);
 	}

src/compile/render-dom/wrappers/Element/index.ts

@@ -389,9 +389,7 @@ export default class ElementWrapper extends Wrapper {
 
 		if (this.bindings.length === 0) return;
 
-		if (this.node.name === 'select' || this.isMediaNode()) {
-			this.renderer.hasComplexBindings = true;
-		}
+		renderer.component.has_reactive_assignments = true;
 
 		const needsLock = this.node.name !== 'input' || !/radio|checkbox|range|color/.test(this.getStaticAttributeValue('type'));
 
@@ -415,7 +413,7 @@ export default class ElementWrapper extends Wrapper {
 
 		groups.forEach(group => {
 			const handler = block.getUniqueName(`${this.var}_${group.events.join('_')}_handler`);
-			this.renderer.component.declarations.push(handler);
+			renderer.component.declarations.push(handler);
 
 			const needsLock = group.bindings.some(binding => binding.needsLock);
 
@@ -521,16 +519,12 @@ export default class ElementWrapper extends Wrapper {
 				.join(' || ');
 
 			if (this.node.name === 'select' || group.bindings.find(binding => binding.name === 'indeterminate' || binding.isReadOnlyMediaAttribute)) {
-				renderer.hasComplexBindings = true;
-
 				block.builders.hydrate.addLine(
 					`if (${someInitialStateIsUndefined}) @add_render_callback(() => ${callee}.call(${this.var}));`
 				);
 			}
 
 			if (group.events[0] === 'resize') {
-				renderer.hasComplexBindings = true;
-
 				block.builders.hydrate.addLine(
 					`@add_render_callback(() => ${callee}.call(${this.var}));`
 				);

src/compile/render-dom/wrappers/InlineComponent/index.ts

@@ -193,6 +193,8 @@ export default class InlineComponentWrapper extends Wrapper {
 		}
 
 		const munged_bindings = this.node.bindings.map(binding => {
+			component.has_reactive_assignments = true;
+
 			const name = component.getUniqueName(`${this.var}_${binding.name}_binding`);
 			component.declarations.push(name);
 

src/compile/render-dom/wrappers/Window.ts

@@ -125,6 +125,8 @@ export default class WindowWrapper extends Wrapper {
 			block.builders.destroy.addBlock(deindent`
 				window.removeEventListener("${event}", ctx.${handler_name});
 			`);
+
+			component.has_reactive_assignments = true;
 		});
 
 		// special case... might need to abstract this out if we add more special cases

test/js/samples/ssr-no-oncreate-etc/expected.js

@@ -64,3 +64,4 @@ SvelteComponent.css = {
 
 var warned = false;
 export default SvelteComponent;
+export { preload };