apply css optimisations to SSR

src/generators/server-side-rendering/index.ts

@@ -1,6 +1,7 @@
 import deindent from '../../utils/deindent';
 import Generator from '../Generator';
 import Block from './Block';
+import preprocess from './preprocess';
 import visit from './visit';
 import { removeNode, removeObjectKey } from '../../utils/removeNode';
 import { Parsed, Node, CompileOptions } from '../../interfaces';
@@ -24,6 +25,8 @@ export class SsrGenerator extends Generator {
 		// in an SSR context, we don't need to include events, methods, oncreate or ondestroy
 		const { templateProperties, defaultExport } = this;
 
+		preprocess(this, parsed.html);
+
 		if (templateProperties.oncreate)
 			removeNode(
 				this.code,

src/generators/server-side-rendering/preprocess.ts

@@ -0,0 +1,90 @@
+import { SsrGenerator } from './index';
+import { Node } from '../../interfaces';
+
+function noop () {}
+
+function isElseIf(node: Node) {
+	return (
+		node && node.children.length === 1 && node.children[0].type === 'IfBlock'
+	);
+}
+
+const preprocessors = {
+	MustacheTag: noop,
+	RawMustacheTag: noop,
+	Text: noop,
+
+	IfBlock: (
+		generator: SsrGenerator,
+		node: Node,
+		elementStack: Node[]
+	) => {
+		function attachBlocks(node: Node) {
+			preprocessChildren(generator, node, elementStack);
+
+			if (isElseIf(node.else)) {
+				attachBlocks(node.else.children[0]);
+			} else if (node.else) {
+				preprocessChildren(
+					generator,
+					node.else,
+					elementStack
+				);
+			}
+		}
+
+		attachBlocks(node);
+	},
+
+	EachBlock: (
+		generator: SsrGenerator,
+		node: Node,
+		elementStack: Node[]
+	) => {
+		preprocessChildren(generator, node, elementStack);
+
+		if (node.else) {
+			preprocessChildren(
+				generator,
+				node.else,
+				elementStack
+			);
+		}
+	},
+
+	Element: (
+		generator: SsrGenerator,
+		node: Node,
+		elementStack: Node[]
+	) => {
+		const isComponent =
+			generator.components.has(node.name) || node.name === ':Self';
+
+		if (!isComponent) {
+			generator.applyCss(node, elementStack);
+		}
+
+		if (node.children.length) {
+			if (isComponent) {
+				preprocessChildren(generator, node, elementStack);
+			} else {
+				preprocessChildren(generator, node, elementStack.concat(node));
+			}
+		}
+	},
+};
+
+function preprocessChildren(
+	generator: SsrGenerator,
+	node: Node,
+	elementStack: Node[]
+) {
+	node.children.forEach((child: Node, i: number) => {
+		const preprocessor = preprocessors[child.type];
+		if (preprocessor) preprocessor(generator, child, elementStack);
+	});
+}
+
+export default function preprocess(generator: SsrGenerator, html: Node) {
+	preprocessChildren(generator, html, []);
+}

src/generators/server-side-rendering/visitors/Element.ts

@@ -56,7 +56,7 @@ export default function visitElement(
 		}
 	});
 
-	if (generator.cssId && (!generator.cascade || generator.elementDepth === 0)) {
+	if (node._needsCssAttribute) {
 		openingTag += ` ${generator.cssId}`;
 	}
 

test/css/index.js

@@ -1,6 +1,6 @@
 import assert from "assert";
 import * as fs from "fs";
-import { env, svelte } from "../helpers.js";
+import { env, normalizeHtml, svelte } from "../helpers.js";
 
 function tryRequire(file) {
 	try {
@@ -23,27 +23,36 @@ describe("css", () => {
 		}
 
 		(solo ? it.only : it)(dir, () => {
-			const config = Object.assign(tryRequire(`./samples/${dir}/_config.js`) || {}, {
-				format: 'iife',
-				name: 'SvelteComponent'	
-			});
+			const config = tryRequire(`./samples/${dir}/_config.js`) || {};
 			const input = fs
 				.readFileSync(`test/css/samples/${dir}/input.html`, "utf-8")
 				.replace(/\s+$/, "");
 
-			const actual = svelte.compile(input, config);
-			fs.writeFileSync(`test/css/samples/${dir}/_actual.css`, actual.css);
+			const dom = svelte.compile(input, Object.assign(config, {
+				format: 'iife',
+				name: 'SvelteComponent'
+			}));
+
+			const ssr = svelte.compile(input, Object.assign(config, {
+				format: 'iife',
+				generate: 'ssr',
+				name: 'SvelteComponent'
+			}));
+
+			assert.equal(dom.css, ssr.css);
+
+			fs.writeFileSync(`test/css/samples/${dir}/_actual.css`, dom.css);
 			const expected = {
 				html: read(`test/css/samples/${dir}/expected.html`),
 				css: read(`test/css/samples/${dir}/expected.css`)
 			};
 
-			assert.equal(actual.css.trim(), expected.css.trim());
+			assert.equal(dom.css.trim(), expected.css.trim());
 
 			// verify that the right elements have scoping selectors
 			if (expected.html !== null) {
 				return env().then(window => {
-					const Component = eval(`(function () { ${actual.code}; return SvelteComponent; }())`);
+					const Component = eval(`(function () { ${dom.code}; return SvelteComponent; }())`);
 					const target = window.document.querySelector("main");
 
 					new Component({ target, data: config.data });
@@ -51,7 +60,19 @@ describe("css", () => {
 
 					fs.writeFileSync(`test/css/samples/${dir}/_actual.html`, html);
 
-					assert.equal(html.trim(), expected.html.trim());
+					// dom
+					assert.equal(
+						normalizeHtml(window, html),
+						normalizeHtml(window, expected.html)
+					);
+
+					// ssr
+					const component = eval(`(function () { ${ssr.code}; return SvelteComponent; }())`);
+
+					assert.equal(
+						normalizeHtml(window, component.render(config.data)),
+						normalizeHtml(window, expected.html)
+					);
 				});
 			}
 		});

test/css/samples/omit-scoping-attribute-attribute-selector/expected.css

@@ -1,4 +1,4 @@
 
-	[data-foo][svelte-2966013849] {
+	[autoplay][svelte-240005720] {
 		color: red;
 	}

test/css/samples/omit-scoping-attribute-attribute-selector/expected.html

@@ -1,2 +1,2 @@
-<div><p svelte-2966013849="" data-foo="true">this is styled</p>
-	<p data-bar="true">this is unstyled</p></div>
+<div><video svelte-240005720 autoplay></video>
+	<video></video></div>

test/css/samples/omit-scoping-attribute-attribute-selector/input.html

@@ -1,10 +1,10 @@
 <div>
-	<p data-foo>this is styled</p>
-	<p data-bar>this is unstyled</p>
+	<video autoplay></video>
+	<video></video>
 </div>
 
 <style>
-	[data-foo] {
+	[autoplay] {
 		color: red;
 	}
 </style>

test/helpers.js

@@ -69,6 +69,20 @@ export function env() {
 function cleanChildren(node) {
 	let previous = null;
 
+	// sort attributes
+	const attributes = Array.from(node.attributes).sort((a, b) => {
+		return a.name < b.name ? -1 : 1;
+	});
+
+	attributes.forEach(attr => {
+		node.removeAttribute(attr.name);
+	});
+
+	attributes.forEach(attr => {
+		node.setAttribute(attr.name, attr.value);
+	});
+
+	// recurse
 	[...node.childNodes].forEach(child => {
 		if (child.nodeType === 8) {
 			// comment
@@ -114,22 +128,23 @@ function cleanChildren(node) {
 	}
 }
 
+export function normalizeHtml(window, html) {
+	const node = window.document.createElement('div');
+	node.innerHTML = html
+		.replace(/>[\s\r\n]+</g, '><')
+		.trim();
+	cleanChildren(node, '');
+	return node.innerHTML;
+}
+
 export function setupHtmlEqual() {
 	return env().then(window => {
 		assert.htmlEqual = (actual, expected, message) => {
-			window.document.body.innerHTML = actual
-				.replace(/>[\s\r\n]+</g, '><')
-				.trim();
-			cleanChildren(window.document.body, '');
-			actual = window.document.body.innerHTML;
-
-			window.document.body.innerHTML = expected
-				.replace(/>[\s\r\n]+</g, '><')
-				.trim();
-			cleanChildren(window.document.body, '');
-			expected = window.document.body.innerHTML;
-
-			assert.deepEqual(actual, expected, message);
+			assert.deepEqual(
+				normalizeHtml(window, actual),
+				normalizeHtml(window, expected),
+				message
+			);
 		};
 	});
 }