add uniqueName for css module classes

lib/css/CssLoadingRuntimeModule.js

@@ -103,7 +103,7 @@ class CssLoadingRuntimeModule extends RuntimeModule {
 		const code = Template.asString([
 			"link = document.createElement('link');",
 			uniqueName
-				? 'link.setAttribute("data-webpack", dataWebpackPrefix + key);'
+				? 'link.setAttribute("data-webpack", uniqueName + ":" + key);'
 				: "",
 			"link.setAttribute(loadingAttribute, 1);",
 			'link.rel = "stylesheet";',
@@ -133,10 +133,24 @@ class CssLoadingRuntimeModule extends RuntimeModule {
 				id => `${JSON.stringify(id)}:0`
 			).join(",")}};`,
 			"",
+			uniqueName
+				? `var uniqueName = ${JSON.stringify(
+						runtimeTemplate.outputOptions.uniqueName
+				  )};`
+				: "// data-webpack is not used as build has no uniqueName",
 			`var loadCssChunkData = ${runtimeTemplate.basicFunction("chunkId, link", [
 				'var data, token = "", token2, exports = {}, exportsWithId = [], i = 0, cc = 1;',
 				"try { if(!link) link = loadStylesheet(chunkId); data = link.sheet.cssRules; data = data[data.length - 1].style; } catch(e) { data = getComputedStyle(document.head); }",
-				'data = data.getPropertyValue("--webpack-" + chunkId);',
+				`data = data.getPropertyValue(${
+					uniqueName
+						? runtimeTemplate.concatenation(
+								"--webpack-",
+								{ expr: "uniqueName" },
+								"-",
+								{ expr: "chunkId" }
+						  )
+						: runtimeTemplate.concatenation("--webpack-", { expr: "chunkId" })
+				});`,
 				"if(!data) return;",
 				"for(; cc; i++) {",
 				Template.indent([
@@ -147,11 +161,23 @@ class CssLoadingRuntimeModule extends RuntimeModule {
 					)}) { exports[token2.replace(/^_/, "")] = token.replace(/^_/, ""); token = ""; }`,
 					`else if(cc == ${cc(
 						"/"
-					)}) { token = token.replace(/^_/, ""); exports[token] = token + "_"; exportsWithId.push(token); token = ""; }`,
+					)}) { token = token.replace(/^_/, ""); exports[token] = token; exportsWithId.push(token); token = ""; }`,
 					`else if(!cc || cc == ${cc(
 						","
 					)}) { token = token.replace(/^_/, ""); exportsWithId.forEach(${runtimeTemplate.expressionFunction(
-						"exports[x] += token",
+						`exports[x] = ${
+							uniqueName
+								? runtimeTemplate.concatenation(
+										{ expr: "uniqueName" },
+										"-",
+										{ expr: "token" },
+										"-",
+										{ expr: "exports[x]" }
+								  )
+								: runtimeTemplate.concatenation({ expr: "token" }, "-", {
+										expr: "exports[x]"
+								  })
+						}`,
 						"x"
 					)}); ${RuntimeGlobals.makeNamespaceObject}(exports); ${
 						RuntimeGlobals.moduleFactories
@@ -166,9 +192,6 @@ class CssLoadingRuntimeModule extends RuntimeModule {
 				"installedChunks[chunkId] = 0;"
 			])}`,
 			'var loadingAttribute = "data-webpack-loading";',
-			uniqueName
-				? `var dataWebpackPrefix = ${JSON.stringify(uniqueName + ":")};`
-				: "// data-webpack is not used as build has no uniqueName",
 			`var loadStylesheet = ${runtimeTemplate.basicFunction(
 				"chunkId, url, done" + (withHmr ? ", hmr" : ""),
 				[
@@ -180,7 +203,7 @@ class CssLoadingRuntimeModule extends RuntimeModule {
 						"var l = links[i];",
 						`if(l.getAttribute("href") == url${
 							uniqueName
-								? ' || l.getAttribute("data-webpack") == dataWebpackPrefix + key'
+								? ' || l.getAttribute("data-webpack") == uniqueName + ":" + key'
 								: ""
 						}) { link = l; break; }`
 					]),

lib/css/CssModulesPlugin.js

@@ -180,7 +180,8 @@ class CssModulesPlugin {
 								this.renderChunk({
 									chunk,
 									chunkGraph,
-									codeGenerationResults
+									codeGenerationResults,
+									uniqueName: compilation.outputOptions.uniqueName
 								}),
 							filenameTemplate: CssModulesPlugin.getChunkFilenameTemplate(
 								chunk,
@@ -240,7 +241,7 @@ class CssModulesPlugin {
 		return [...(cssImports || []), ...(cssContent || [])];
 	}
 
-	renderChunk({ chunk, chunkGraph, codeGenerationResults }) {
+	renderChunk({ uniqueName, chunk, chunkGraph, codeGenerationResults }) {
 		const modules = this.getOrderedChunkCssModules(chunk, chunkGraph);
 		const source = new ConcatSource();
 		const metaData = [];
@@ -262,7 +263,7 @@ class CssModulesPlugin {
 					`${
 						exports
 							? Array.from(exports, ([n, v]) =>
-									v === `${n}_${moduleId}`
+									v === `${uniqueName ? uniqueName + "-" : ""}${moduleId}-${n}`
 										? `${escapeCss(n)}/`
 										: `${escapeCss(n)}(${escapeCss(v)})`
 							  ).join("")
@@ -275,7 +276,10 @@ class CssModulesPlugin {
 			}
 		}
 		source.add(
-			`head{--webpack-${escapeCss(chunk.id, true)}:${metaData.join(",")};}`
+			`head{--webpack-${escapeCss(
+				(uniqueName ? uniqueName + "-" : "") + chunk.id,
+				true
+			)}:${metaData.join(",")};}`
 		);
 		return source;
 	}

lib/dependencies/CssLocalIdentifierDependency.js

@@ -83,14 +83,20 @@ CssLocalIdentifierDependency.Template = class CssLocalIdentifierDependencyTempla
 	apply(
 		dependency,
 		source,
-		{ module, moduleGraph, chunkGraph, runtime, cssExports }
+		{ module, moduleGraph, chunkGraph, runtime, runtimeTemplate, cssExports }
 	) {
 		const dep = /** @type {CssLocalIdentifierDependency} */ (dependency);
 		const used = moduleGraph
 			.getExportInfo(module, dep.name)
 			.getUsedName(dep.name, runtime);
 		const moduleId = chunkGraph.getModuleId(module);
-		const identifier = (used || "_") + "_" + moduleId;
+		const identifier =
+			(runtimeTemplate.outputOptions.uniqueName
+				? runtimeTemplate.outputOptions.uniqueName + "-"
+				: "") +
+			moduleId +
+			"-" +
+			(used || "");
 		source.replace(
 			dep.range[0],
 			dep.range[1] - 1,

test/configCases/css/css-modules/index.js

@@ -8,16 +8,16 @@ it("should allow to create css modules", done => {
 		try {
 			expect(x).toEqual({
 				global: undefined,
-				class: prod ? "S_491" : "class_./style.module.css",
+				class: prod ? "my-app-491-S" : "./style.module.css-class",
 				local: prod
-					? "Zw_491 yl_491 J__491 gc_491"
-					: "local1_./style.module.css local2_./style.module.css local3_./style.module.css local4_./style.module.css",
+					? "my-app-491-Zw my-app-491-yl my-app-491-J_ my-app-491-gc"
+					: "./style.module.css-local1 ./style.module.css-local2 ./style.module.css-local3 ./style.module.css-local4",
 				local2: prod
-					? "Xg_491 AY_491"
-					: "local5_./style.module.css local6_./style.module.css",
+					? "my-app-491-Xg my-app-491-AY"
+					: "./style.module.css-local5 ./style.module.css-local6",
 				nested: prod
-					? "RX_491 undefined X2_491"
-					: "nested1_./style.module.css undefined nested3_./style.module.css"
+					? "my-app-491-RX undefined my-app-491-X2"
+					: "./style.module.css-nested1 undefined ./style.module.css-nested3"
 			});
 		} catch (e) {
 			return done(e);

test/configCases/css/css-modules/webpack.config.js

@@ -10,6 +10,9 @@ module.exports = [
 	{
 		target: "web",
 		mode: "production",
+		output: {
+			uniqueName: "my-app"
+		},
 		experiments: {
 			css: true
 		}