support !important in style directive

src/compiler/compile/nodes/StyleDirective.ts

@@ -10,6 +10,7 @@ export default class StyleDirective extends Node {
 	name: string;
 	expression: Expression;
 	should_cache: boolean;
+	important: boolean = false;
 
 	constructor(component: Component, parent: Node, scope: TemplateScope, info: TemplateNode) {
 		super(component, parent, scope, info);
@@ -30,10 +31,16 @@ export default class StyleDirective extends Node {
 			this.expression = new Expression(component, this, scope, identifier);
 			this.should_cache = false;
 		} else {
+			const last_chunk = info.value[info.value.length - 1];
+			if (last_chunk && last_chunk.type === 'Text' && /\s*!important\s*;?\s*$/.test(last_chunk.data)) {
+				this.important = true;
+				last_chunk.data = last_chunk.data.replace(/\s*!important\s*;?\s*$/, '');
+				if (!last_chunk.data) info.value.pop();
+			}
+
 			const raw_expression = nodes_to_template_literal(info.value);
 			this.expression = new Expression(component, this, scope, raw_expression);
 			this.should_cache = raw_expression.expressions.length > 0;
 		}
-
 	}
 }

src/compiler/compile/render_dom/wrappers/Element/index.ts

@@ -1072,7 +1072,7 @@ export default class ElementWrapper extends Wrapper {
 	add_styles(block: Block) {
 		const has_spread = this.node.attributes.some(attr => attr.is_spread);
 		this.node.styles.forEach((style_directive) => {
-			const { name, expression, should_cache } = style_directive;
+			const { name, expression, should_cache, important } = style_directive;
 
 			const snippet = expression.manipulate(block);
 			let cached_snippet;
@@ -1081,7 +1081,7 @@ export default class ElementWrapper extends Wrapper {
 				block.add_variable(cached_snippet, snippet);
 			}
 
-			const updater = b`@set_style(${this.var}, "${name}", ${should_cache ? cached_snippet : snippet}, false)`;
+			const updater = b`@set_style(${this.var}, "${name}", ${should_cache ? cached_snippet : snippet}, ${important ? 'true' : 'false'})`;
 
 			block.chunks.hydrate.push(updater);
 

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

@@ -40,7 +40,10 @@ export default function (node: Element, renderer: Renderer, options: RenderOptio
 		class_expression_list.reduce((lhs, rhs) => x`${lhs} + ' ' + ${rhs}`);
 
 	const style_expression_list = node.styles.map(style_directive => {
-		const { name, expression: { node: expression } } = style_directive;
+		let { name, important, expression: { node: expression } } = style_directive;
+		if (important) {
+			expression = x`${expression} + ' !important'`;
+		}
 		return p`"${name}": ${expression}`;
 	});
 

test/runtime-puppeteer/samples/inline-style-directive-important/_config.js

@@ -0,0 +1,34 @@
+export default {
+	html: `
+		<h1 class="svelte-udf14z" style="background-color: red;">hello</h1>
+		<h1 class="svelte-udf14z">hello</h1>
+		<h1 class="svelte-udf14z" style="background-color: red !important;">hello</h1>
+		<h1 class="svelte-udf14z" style="background-color: red !important;">hello</h1>
+		<h1 class="svelte-udf14z" style="background-color: red !important;">hello</h1>
+		<h2 class="svelte-udf14z" style="--background-color:red;">hello</h2>
+		<h2 class="svelte-udf14z" style="--background-color:red !important;">hello</h2>
+	`,
+
+	ssrHtml: `
+		<h1 class="svelte-udf14z" style="background-color: red;">hello</h1>
+		<h1 class="svelte-udf14z" style="background-color: red important;">hello</h1>
+		<h1 class="svelte-udf14z" style="background-color: red !important;">hello</h1>
+		<h1 class="svelte-udf14z" style="background-color: red !important;">hello</h1>
+		<h1 class="svelte-udf14z" style="background-color: red !important">hello</h1>
+		<h2 class="svelte-udf14z" style="--background-color: red;">hello</h2>
+		<h2 class="svelte-udf14z" style="--background-color: red !important;">hello</h2>
+	`,
+
+	test({ assert, target, window }) {
+		const h1s = target.querySelectorAll('h1');
+		const h2s = target.querySelectorAll('h2');
+
+		assert.equal(window.getComputedStyle(h1s[0])['backgroundColor'], 'rgb(0, 0, 255)');
+		assert.equal(window.getComputedStyle(h1s[1])['backgroundColor'], 'rgb(0, 0, 255)');
+		assert.equal(window.getComputedStyle(h1s[2])['backgroundColor'], 'rgb(255, 0, 0)');
+		assert.equal(window.getComputedStyle(h1s[3])['backgroundColor'], 'rgb(255, 0, 0)');
+		assert.equal(window.getComputedStyle(h1s[4])['backgroundColor'], 'rgb(255, 0, 0)');
+		assert.equal(window.getComputedStyle(h2s[0])['backgroundColor'], 'rgb(0, 0, 255)');
+		assert.equal(window.getComputedStyle(h2s[1])['backgroundColor'], 'rgb(255, 0, 0)');
+	}
+};

test/runtime-puppeteer/samples/inline-style-directive-important/main.svelte

@@ -0,0 +1,21 @@
+<script>
+	export let color = 'red'
+</script>
+
+<h1 style:background-color={color} >hello</h1>
+<h1 style:background-color="{color} important">hello</h1>
+<h1 style:background-color="{color} !important">hello</h1>
+<h1 style:background-color="{color} !important;">hello</h1>
+<h1 style="background-color: {color} !important">hello</h1>
+<h2 style:--background-color={color}>hello</h2>
+<h2 style:--background-color="{color} !important;">hello</h2>
+
+<style>
+	h1 {
+		background-color: blue !important;
+	}
+	h2 {
+		--background-color: blue !important;
+		background-color: var(--background-color);
+	}
+</style> 

test/runtime/samples/inline-style-directive-important/_config.js

@@ -0,0 +1,27 @@
+export default {
+	html: `
+		<h1 class="svelte-szzkfu" style="background-color: red;">hello</h1>
+		<h1 class="svelte-szzkfu">hello</h1>
+		<h1 class="svelte-szzkfu" style="background-color: red;">hello</h1>
+		<h1 class="svelte-szzkfu" style="background-color: red;">hello</h1>
+		<h1 class="svelte-szzkfu" style="background-color: red;">hello</h1>
+	`,
+
+	ssrHtml: `
+		<h1 class="svelte-szzkfu" style="background-color: red;">hello</h1>
+		<h1 class="svelte-szzkfu" style="background-color: red important;">hello</h1>
+		<h1 class="svelte-szzkfu" style="background-color: red !important;">hello</h1>
+		<h1 class="svelte-szzkfu" style="background-color: red !important;">hello</h1>
+		<h1 class="svelte-szzkfu" style="background-color: red !important">hello</h1>
+	`,
+
+	test({ assert, target, window }) {
+		const h1s = target.querySelectorAll('h1');
+
+		assert.equal(window.getComputedStyle(h1s[0])['backgroundColor'], 'red');
+		assert.equal(window.getComputedStyle(h1s[1])['backgroundColor'], 'blue');
+		assert.equal(window.getComputedStyle(h1s[2])['backgroundColor'], 'red');
+		assert.equal(window.getComputedStyle(h1s[3])['backgroundColor'], 'red');
+		assert.equal(window.getComputedStyle(h1s[4])['backgroundColor'], 'red');
+	}
+};

test/runtime/samples/inline-style-directive-important/main.svelte

@@ -0,0 +1,15 @@
+<script>
+	export let color = 'red'
+</script>
+
+<h1 style:background-color={color} >hello</h1>
+<h1 style:background-color="{color} important">hello</h1>
+<h1 style:background-color="{color} !important">hello</h1>
+<h1 style:background-color="{color} !important;">hello</h1>
+<h1 style="background-color: {color} !important">hello</h1>
+
+<style>
+	h1 {
+		background-color: blue !important;
+	}
+</style>