diff --git a/lib/AbstractMethodError.js b/lib/AbstractMethodError.js
index 527d224a473..e149cd600f3 100644
--- a/lib/AbstractMethodError.js
+++ b/lib/AbstractMethodError.js
@@ -13,9 +13,8 @@ const CURRENT_METHOD_REGEXP = /at ([a-zA-Z0-9_.]*)/;
  * @param {string=} method method name
  * @returns {string} message
  */
-function createMessage(method) {
-	return `Abstract method${method ? ` ${method}` : ""}. Must be overridden.`;
-}
+const createMessage = (method) =>
+	`Abstract method${method ? ` ${method}` : ""}. Must be overridden.`;
 
 /**
  * @constructor
diff --git a/lib/DefinePlugin.js b/lib/DefinePlugin.js
index c52558d7518..3cae3084762 100644
--- a/lib/DefinePlugin.js
+++ b/lib/DefinePlugin.js
@@ -127,10 +127,10 @@ class RuntimeValue {
  * @param {DestructuringAssignmentProperties | undefined} properties properties
  * @returns {Set<string> | undefined} used keys
  */
-function getObjKeys(properties) {
+const getObjKeys = (properties) => {
 	if (!properties) return;
 	return new Set([...properties].map((p) => p.id));
-}
+};
 
 /** @typedef {Set<string> | null} ObjKeys */
 /** @typedef {boolean | undefined | null} AsiSafe */
diff --git a/lib/RuntimeTemplate.js b/lib/RuntimeTemplate.js
index 3b868e5deac..d713de7f293 100644
--- a/lib/RuntimeTemplate.js
+++ b/lib/RuntimeTemplate.js
@@ -325,9 +325,7 @@ class RuntimeTemplate {
 	forEach(variable, array, body) {
 		return this.supportsForOf()
 			? `for(const ${variable} of ${array}) {\n${Template.indent(body)}\n}`
-			: `${array}.forEach(function(${variable}) {\n${Template.indent(
-					body
-				)}\n});`;
+			: `${array}.forEach((${variable}) => {\n${Template.indent(body)}\n});`;
 	}
 
 	/**
diff --git a/lib/async-modules/AwaitDependenciesInitFragment.js b/lib/async-modules/AwaitDependenciesInitFragment.js
index a0a25a8e832..59ca019f4d6 100644
--- a/lib/async-modules/AwaitDependenciesInitFragment.js
+++ b/lib/async-modules/AwaitDependenciesInitFragment.js
@@ -55,7 +55,7 @@ class AwaitDependenciesInitFragment extends InitFragment {
 		const asyncModuleValues = [...this.dependencies.values()].join(", ");
 
 		const templateInput = [
-			`var __webpack_async_dependencies__ = __webpack_handle_async_dependencies__([${asyncModuleValues}]);`
+			`const __webpack_async_dependencies__ = __webpack_handle_async_dependencies__([${asyncModuleValues}]);`
 		];
 
 		if (
@@ -63,7 +63,7 @@ class AwaitDependenciesInitFragment extends InitFragment {
 			!runtimeTemplate.supportsDestructuring()
 		) {
 			templateInput.push(
-				"var __webpack_async_dependencies_result__ = (__webpack_async_dependencies__.then ? (await __webpack_async_dependencies__)() : __webpack_async_dependencies__);"
+				"const __webpack_async_dependencies_result__ = (__webpack_async_dependencies__.then ? (await __webpack_async_dependencies__)() : __webpack_async_dependencies__);"
 			);
 			for (const [index, importVar] of importVars.entries()) {
 				templateInput.push(
diff --git a/lib/container/ContainerEntryModule.js b/lib/container/ContainerEntryModule.js
index 987025d3a4c..b552299f071 100644
--- a/lib/container/ContainerEntryModule.js
+++ b/lib/container/ContainerEntryModule.js
@@ -226,7 +226,7 @@ class ContainerEntryModule extends Module {
 			`var init = ${runtimeTemplate.basicFunction("shareScope, initScope", [
 				`if (!${RuntimeGlobals.shareScopeMap}) return;`,
 				`var name = ${JSON.stringify(this._shareScope)}`,
-				`var oldScope = ${RuntimeGlobals.shareScopeMap}[name];`,
+				`const oldScope = ${RuntimeGlobals.shareScopeMap}[name];`,
 				'if(oldScope && oldScope !== shareScope) throw new Error("Container initialization failed as it has already been initialized with a different share scope");',
 				`${RuntimeGlobals.shareScopeMap}[name] = shareScope;`,
 				`return ${RuntimeGlobals.initializeSharing}(name, initScope);`
diff --git a/lib/container/FallbackModule.js b/lib/container/FallbackModule.js
index 29dd647b9f0..66dee1fa9ef 100644
--- a/lib/container/FallbackModule.js
+++ b/lib/container/FallbackModule.js
@@ -134,9 +134,9 @@ class FallbackModule extends Module {
 			chunkGraph.getModuleId(/** @type {Module} */ (moduleGraph.getModule(dep)))
 		);
 		const code = Template.asString([
-			`var ids = ${JSON.stringify(ids)};`,
-			"var error, result, i = 0;",
-			`var loop = ${runtimeTemplate.basicFunction("next", [
+			`const ids = ${JSON.stringify(ids)};`,
+			"let error, result, i = 0;",
+			`const loop = ${runtimeTemplate.basicFunction("next", [
 				"while(i < ids.length) {",
 				Template.indent([
 					`try { next = ${RuntimeGlobals.require}(ids[i++]); } catch(e) { return handleError(e); }`,
@@ -145,11 +145,11 @@ class FallbackModule extends Module {
 				"}",
 				"if(error) throw error;"
 			])}`,
-			`var handleResult = ${runtimeTemplate.basicFunction("result", [
+			`const handleResult = ${runtimeTemplate.basicFunction("result", [
 				"if(result) return result;",
 				"return loop();"
 			])};`,
-			`var handleError = ${runtimeTemplate.basicFunction("e", [
+			`const handleError = ${runtimeTemplate.basicFunction("e", [
 				"error = e;",
 				"return loop();"
 			])};`,
diff --git a/lib/container/RemoteRuntimeModule.js b/lib/container/RemoteRuntimeModule.js
index c44e8ccf71a..fdd9cfc7e21 100644
--- a/lib/container/RemoteRuntimeModule.js
+++ b/lib/container/RemoteRuntimeModule.js
@@ -76,9 +76,9 @@ class RemoteRuntimeModule extends RuntimeModule {
 				`if(${RuntimeGlobals.hasOwnProperty}(chunkMapping, chunkId)) {`,
 				Template.indent([
 					`chunkMapping[chunkId].forEach(${runtimeTemplate.basicFunction("id", [
-						`var getScope = ${RuntimeGlobals.currentRemoteGetScope};`,
+						`let getScope = ${RuntimeGlobals.currentRemoteGetScope};`,
 						"if(!getScope) getScope = [];",
-						"var data = idToExternalAndNameMapping[id];",
+						"const data = idToExternalAndNameMapping[id];",
 						"if(getScope.indexOf(data) >= 0) return;",
 						"getScope.push(data);",
 						"if(data.p) return promises.push(data.p);",
@@ -98,10 +98,10 @@ class RemoteRuntimeModule extends RuntimeModule {
 							[
 								"try {",
 								Template.indent([
-									"var promise = fn(arg1, arg2);",
+									"const promise = fn(arg1, arg2);",
 									"if(promise && promise.then) {",
 									Template.indent([
-										`var p = promise.then(${runtimeTemplate.returningFunction(
+										`const p = promise.then(${runtimeTemplate.returningFunction(
 											"next(result, d)",
 											"result"
 										)}, onError);`,
diff --git a/lib/css/CssLoadingRuntimeModule.js b/lib/css/CssLoadingRuntimeModule.js
index 2af0c8aa8ae..ab04f22e9a5 100644
--- a/lib/css/CssLoadingRuntimeModule.js
+++ b/lib/css/CssLoadingRuntimeModule.js
@@ -191,18 +191,18 @@ class CssLoadingRuntimeModule extends RuntimeModule {
 				: "// data-webpack is not used as build has no uniqueName",
 			withLoading || withHmr
 				? Template.asString([
-						'var loadingAttribute = "data-webpack-loading";',
+						'const loadingAttribute = "data-webpack-loading";',
 						`var loadStylesheet = ${runtimeTemplate.basicFunction(
 							`chunkId, url, done${
 								withFetchPriority ? ", fetchPriority" : ""
 							}${withHmr ? ", hmr" : ""}`,
 							[
-								'var link, needAttach, key = "chunk-" + chunkId;',
+								'let link, needAttach; const key = "chunk-" + chunkId;',
 								withHmr ? "if(!hmr) {" : "",
-								'var links = document.getElementsByTagName("link");',
-								"for(var i = 0; i < links.length; i++) {",
+								'const links = document.getElementsByTagName("link");',
+								"for(let i = 0; i < links.length; i++) {",
 								Template.indent([
-									"var l = links[i];",
+									"const l = links[i];",
 									`if(l.rel == "stylesheet" && (${
 										withHmr
 											? 'l.href.startsWith(url) || l.getAttribute("href").startsWith(url)'
@@ -235,7 +235,7 @@ class CssLoadingRuntimeModule extends RuntimeModule {
 								)};`,
 								"if(link.getAttribute(loadingAttribute)) {",
 								Template.indent([
-									`var timeout = setTimeout(onLinkComplete.bind(null, undefined, { type: 'timeout', target: link }), ${loadTimeout});`,
+									`const timeout = setTimeout(onLinkComplete.bind(null, undefined, { type: 'timeout', target: link }), ${loadTimeout});`,
 									"link.onerror = onLinkComplete.bind(null, link.onerror);",
 									"link.onload = onLinkComplete.bind(null, link.onload);"
 								]),
@@ -256,7 +256,7 @@ class CssLoadingRuntimeModule extends RuntimeModule {
 							`chunkId, promises${withFetchPriority ? " , fetchPriority" : ""}`,
 							[
 								"// css chunk loading",
-								`var installedChunkData = ${RuntimeGlobals.hasOwnProperty}(installedChunks, chunkId) ? installedChunks[chunkId] : undefined;`,
+								`let installedChunkData = ${RuntimeGlobals.hasOwnProperty}(installedChunks, chunkId) ? installedChunks[chunkId] : undefined;`,
 								'if(installedChunkData !== 0) { // 0 means "already installed".',
 								Template.indent([
 									"",
@@ -270,17 +270,17 @@ class CssLoadingRuntimeModule extends RuntimeModule {
 											: `if(${hasCssMatcher("chunkId")}) {`,
 										Template.indent([
 											"// setup Promise in chunk cache",
-											`var promise = new Promise(${runtimeTemplate.expressionFunction(
+											`const promise = new Promise(${runtimeTemplate.expressionFunction(
 												"installedChunkData = installedChunks[chunkId] = [resolve, reject]",
 												"resolve, reject"
 											)});`,
 											"promises.push(installedChunkData[2] = promise);",
 											"",
 											"// start chunk loading",
-											`var url = ${RuntimeGlobals.publicPath} + ${RuntimeGlobals.getChunkCssFilename}(chunkId);`,
+											`const url = ${RuntimeGlobals.publicPath} + ${RuntimeGlobals.getChunkCssFilename}(chunkId);`,
 											"// create error before stack unwound to get useful stacktrace later",
-											"var error = new Error();",
-											`var loadingEnded = ${runtimeTemplate.basicFunction(
+											"const error = new Error();",
+											`const loadingEnded = ${runtimeTemplate.basicFunction(
 												"event",
 												[
 													`if(${RuntimeGlobals.hasOwnProperty}(installedChunks, chunkId)) {`,
@@ -291,8 +291,8 @@ class CssLoadingRuntimeModule extends RuntimeModule {
 														Template.indent([
 															'if(event.type !== "load") {',
 															Template.indent([
-																"var errorType = event && event.type;",
-																"var realHref = event && event.target && event.target.href;",
+																"const errorType = event && event.type;",
+																"const realHref = event && event.target && event.target.href;",
 																"error.message = 'Loading css chunk ' + chunkId + ' failed.\\n(' + errorType + ': ' + realHref + ')';",
 																"error.name = 'ChunkLoadError';",
 																"error.type = errorType;",
@@ -349,7 +349,7 @@ class CssLoadingRuntimeModule extends RuntimeModule {
 								: "",
 							linkPrefetch.call(
 								Template.asString([
-									"var link = document.createElement('link');",
+									"const link = document.createElement('link');",
 									charset ? "link.charset = 'utf-8';" : "",
 									crossOriginLoading
 										? `link.crossOrigin = ${JSON.stringify(
@@ -389,7 +389,7 @@ class CssLoadingRuntimeModule extends RuntimeModule {
 								: "",
 							linkPreload.call(
 								Template.asString([
-									"var link = document.createElement('link');",
+									"const link = document.createElement('link');",
 									charset ? "link.charset = 'utf-8';" : "",
 									`if (${RuntimeGlobals.scriptNonce}) {`,
 									Template.indent(
@@ -422,20 +422,20 @@ class CssLoadingRuntimeModule extends RuntimeModule {
 				: "// no preloaded",
 			withHmr
 				? Template.asString([
-						"var oldTags = [];",
-						"var newTags = [];",
+						"const oldTags = [];",
+						"const newTags = [];",
 						`var applyHandler = ${runtimeTemplate.basicFunction("options", [
 							`return { dispose: ${runtimeTemplate.basicFunction("", [
 								"while(oldTags.length) {",
 								Template.indent([
-									"var oldTag = oldTags.pop();",
+									"const oldTag = oldTags.pop();",
 									"if(oldTag.parentNode) oldTag.parentNode.removeChild(oldTag);"
 								]),
 								"}"
 							])}, apply: ${runtimeTemplate.basicFunction("", [
 								"while(newTags.length) {",
 								Template.indent([
-									"var newTag = newTags.pop();",
+									"const newTag = newTags.pop();",
 									"newTag.sheet.disabled = false"
 								]),
 								"}"
@@ -458,9 +458,9 @@ class CssLoadingRuntimeModule extends RuntimeModule {
 									: "",
 								"applyHandlers.push(applyHandler);",
 								`chunkIds.forEach(${runtimeTemplate.basicFunction("chunkId", [
-									`var filename = ${RuntimeGlobals.getChunkCssFilename}(chunkId);`,
-									`var url = ${RuntimeGlobals.publicPath} + filename;`,
-									"var oldTag = loadStylesheet(chunkId, url);",
+									`const filename = ${RuntimeGlobals.getChunkCssFilename}(chunkId);`,
+									`const url = ${RuntimeGlobals.publicPath} + filename;`,
+									"const oldTag = loadStylesheet(chunkId, url);",
 									"if(!oldTag) return;",
 									`promises.push(new Promise(${runtimeTemplate.basicFunction(
 										"resolve, reject",
@@ -470,8 +470,8 @@ class CssLoadingRuntimeModule extends RuntimeModule {
 												[
 													'if(event.type !== "load") {',
 													Template.indent([
-														"var errorType = event && event.type;",
-														"var realHref = event && event.target && event.target.href;",
+														"const errorType = event && event.type;",
+														"const realHref = event && event.target && event.target.href;",
 														"error.message = 'Loading css hot update chunk ' + chunkId + ' failed.\\n(' + errorType + ': ' + realHref + ')';",
 														"error.name = 'ChunkLoadError';",
 														"error.type = errorType;",
diff --git a/lib/css/CssModulesPlugin.js b/lib/css/CssModulesPlugin.js
index 89341e1a908..ac88bc01069 100644
--- a/lib/css/CssModulesPlugin.js
+++ b/lib/css/CssModulesPlugin.js
@@ -411,7 +411,7 @@ class CssModulesPlugin {
 
 						const hmrCode = Template.asString([
 							"",
-							`var __webpack_css_exports__ = ${stringifiedExports};`,
+							`const __webpack_css_exports__ = ${stringifiedExports};`,
 							"// only invalidate when locals change",
 							"if (module.hot.data && module.hot.data.__webpack_css_exports__ && module.hot.data.__webpack_css_exports__ != __webpack_css_exports__) {",
 							Template.indent("module.hot.invalidate();"),
diff --git a/lib/esm/ModuleChunkLoadingRuntimeModule.js b/lib/esm/ModuleChunkLoadingRuntimeModule.js
index 453320c8111..69688a671a9 100644
--- a/lib/esm/ModuleChunkLoadingRuntimeModule.js
+++ b/lib/esm/ModuleChunkLoadingRuntimeModule.js
@@ -205,7 +205,7 @@ class ModuleChunkLoadingRuntimeModule extends RuntimeModule {
 							hasJsMatcher !== false
 								? Template.indent([
 										"// import() chunk loading for javascript",
-										`var installedChunkData = ${RuntimeGlobals.hasOwnProperty}(installedChunks, chunkId) ? installedChunks[chunkId] : undefined;`,
+										`const installedChunkData = ${RuntimeGlobals.hasOwnProperty}(installedChunks, chunkId) ? installedChunks[chunkId] : undefined;`,
 										'if(installedChunkData !== 0) { // 0 means "already installed".',
 										Template.indent([
 											"",
@@ -269,7 +269,7 @@ class ModuleChunkLoadingRuntimeModule extends RuntimeModule {
 							"installedChunks[chunkId] = null;",
 							linkPrefetch.call(
 								Template.asString([
-									"var link = document.createElement('link');",
+									"const link = document.createElement('link');",
 									charset ? "link.charset = 'utf-8';" : "",
 									crossOriginLoading
 										? `link.crossOrigin = ${JSON.stringify(
@@ -309,7 +309,7 @@ class ModuleChunkLoadingRuntimeModule extends RuntimeModule {
 							"installedChunks[chunkId] = null;",
 							linkPreload.call(
 								Template.asString([
-									"var link = document.createElement('link');",
+									"const link = document.createElement('link');",
 									charset ? "link.charset = 'utf-8';" : "",
 									`if (${RuntimeGlobals.scriptNonce}) {`,
 									Template.indent(
@@ -364,10 +364,10 @@ class ModuleChunkLoadingRuntimeModule extends RuntimeModule {
 								"resolve, reject",
 								[
 									"// start update chunk loading",
-									`var url = ${RuntimeGlobals.publicPath} + ${RuntimeGlobals.getChunkUpdateScriptFilename}(chunkId);`,
+									`const url = ${RuntimeGlobals.publicPath} + ${RuntimeGlobals.getChunkUpdateScriptFilename}(chunkId);`,
 									`var onResolve = ${runtimeTemplate.basicFunction("obj", [
-										`var updatedModules = obj.${RuntimeGlobals.esmModules};`,
-										`var updatedRuntime = obj.${RuntimeGlobals.esmRuntime};`,
+										`const updatedModules = obj.${RuntimeGlobals.esmModules};`,
+										`const updatedRuntime = obj.${RuntimeGlobals.esmRuntime};`,
 										"if(updatedRuntime) currentUpdateRuntime.push(updatedRuntime);",
 										"for(var moduleId in updatedModules) {",
 										Template.indent([
@@ -382,7 +382,7 @@ class ModuleChunkLoadingRuntimeModule extends RuntimeModule {
 										"resolve(obj);"
 									])};`,
 									`var onReject = ${runtimeTemplate.basicFunction("error", [
-										"var errorMsg = error.message || 'unknown reason';",
+										"const errorMsg = error.message || 'unknown reason';",
 										"error.message = 'Loading hot update chunk ' + chunkId + ' failed.\\n(' + errorMsg + ')';",
 										"error.name = 'ChunkLoadError';",
 										"reject(error);"
diff --git a/lib/hmr/LazyCompilationPlugin.js b/lib/hmr/LazyCompilationPlugin.js
index a7791899b58..f182b74a0bf 100644
--- a/lib/hmr/LazyCompilationPlugin.js
+++ b/lib/hmr/LazyCompilationPlugin.js
@@ -239,10 +239,10 @@ class LazyCompilationProxyModule extends Module {
 				request: clientDep.userRequest,
 				runtimeRequirements
 			})}`,
-			`var data = ${JSON.stringify(this.data)};`
+			`const data = ${JSON.stringify(this.data)};`
 		]);
 		const keepActive = Template.asString([
-			`var dispose = client.keepAlive({ data: data, active: ${JSON.stringify(
+			`const dispose = client.keepAlive({ data: data, active: ${JSON.stringify(
 				Boolean(block)
 			)}, module: module, onError: onError });`
 		]);
@@ -277,8 +277,8 @@ class LazyCompilationProxyModule extends Module {
 		} else {
 			source = Template.asString([
 				client,
-				"var resolveSelf, onError;",
-				"module.exports = new Promise(function(resolve, reject) { resolveSelf = resolve; onError = reject; });",
+				"let resolveSelf, onError;",
+				"module.exports = new Promise((resolve, reject) => { resolveSelf = resolve; onError = reject; });",
 				"if (module.hot) {",
 				Template.indent([
 					"module.hot.accept();",
diff --git a/lib/javascript/CommonJsChunkFormatPlugin.js b/lib/javascript/CommonJsChunkFormatPlugin.js
index 9ce41aa1a33..34a5115051a 100644
--- a/lib/javascript/CommonJsChunkFormatPlugin.js
+++ b/lib/javascript/CommonJsChunkFormatPlugin.js
@@ -106,11 +106,11 @@ class CommonJsChunkFormatPlugin {
 							runtimeTemplate.supportsArrowFunction() ? "() => " : "function() "
 						}{\n`
 					);
-					entrySource.add("var exports = {};\n");
+					entrySource.add("const exports = {};\n");
 					entrySource.add(source);
 					entrySource.add(";\n\n// load runtime\n");
 					entrySource.add(
-						`var ${RuntimeGlobals.require} = require(${JSON.stringify(
+						`const ${RuntimeGlobals.require} = require(${JSON.stringify(
 							runtimePath
 						)});\n`
 					);
diff --git a/lib/javascript/JavascriptModulesPlugin.js b/lib/javascript/JavascriptModulesPlugin.js
index 699e0d7b228..45cef625e33 100644
--- a/lib/javascript/JavascriptModulesPlugin.js
+++ b/lib/javascript/JavascriptModulesPlugin.js
@@ -1507,7 +1507,7 @@ class JavascriptModulesPlugin {
 		)
 			? Template.asString([
 					`var execOptions = { id: moduleId, module: module, factory: __webpack_modules__[moduleId], require: ${RuntimeGlobals.require} };`,
-					`${RuntimeGlobals.interceptModuleExecution}.forEach(function(handler) { handler(execOptions); });`,
+					`${RuntimeGlobals.interceptModuleExecution}.forEach((handler) => { handler(execOptions); });`,
 					"module = execOptions.module;",
 					"execOptions.factory.call(module.exports, module, module.exports, execOptions.require);"
 				])
diff --git a/lib/library/AssignLibraryPlugin.js b/lib/library/AssignLibraryPlugin.js
index f8f00df1803..298f87e661f 100644
--- a/lib/library/AssignLibraryPlugin.js
+++ b/lib/library/AssignLibraryPlugin.js
@@ -342,12 +342,12 @@ class AssignLibraryPlugin extends AbstractLibraryPlugin {
 			let exports = RuntimeGlobals.exports;
 			if (exportAccess) {
 				result.add(
-					`var __webpack_exports_export__ = ${RuntimeGlobals.exports}${exportAccess};\n`
+					`const __webpack_exports_export__ = ${RuntimeGlobals.exports}${exportAccess};\n`
 				);
 
 				exports = "__webpack_exports_export__";
 			}
-			result.add(`for(var __webpack_i__ in ${exports}) {\n`);
+			result.add(`for(const __webpack_i__ in ${exports}) {\n`);
 			const hasProvided = provided.length > 0;
 			if (hasProvided) {
 				result.add(
@@ -368,7 +368,7 @@ class AssignLibraryPlugin extends AbstractLibraryPlugin {
 			);
 		} else if (options.name ? this.named === "copy" : this.unnamed === "copy") {
 			result.add(
-				`var __webpack_export_target__ = ${accessWithInit(
+				`const __webpack_export_target__ = ${accessWithInit(
 					fullNameResolved,
 					this._getPrefix(compilation).length,
 					true
@@ -378,13 +378,13 @@ class AssignLibraryPlugin extends AbstractLibraryPlugin {
 			let exports = RuntimeGlobals.exports;
 			if (exportAccess) {
 				result.add(
-					`var __webpack_exports_export__ = ${RuntimeGlobals.exports}${exportAccess};\n`
+					`const __webpack_exports_export__ = ${RuntimeGlobals.exports}${exportAccess};\n`
 				);
 
 				exports = "__webpack_exports_export__";
 			}
 			result.add(
-				`for(var __webpack_i__ in ${exports}) __webpack_export_target__[__webpack_i__] = ${exports}[__webpack_i__];\n`
+				`for(const __webpack_i__ in ${exports}) __webpack_export_target__[__webpack_i__] = ${exports}[__webpack_i__];\n`
 			);
 			result.add(
 				`if(${exports}.__esModule) Object.defineProperty(__webpack_export_target__, "__esModule", { value: true });\n`
diff --git a/lib/library/SystemLibraryPlugin.js b/lib/library/SystemLibraryPlugin.js
index 38096209174..e9627e964ce 100644
--- a/lib/library/SystemLibraryPlugin.js
+++ b/lib/library/SystemLibraryPlugin.js
@@ -161,7 +161,7 @@ class SystemLibraryPlugin extends AbstractLibraryPlugin {
 											);
 											instructions.push(
 												Template.asString([
-													"Object.keys(module).forEach(function(key) {",
+													"Object.keys(module).forEach((key) => {",
 													Template.indent([
 														`if(${name}.indexOf(key) >= 0)`,
 														Template.indent(`${external}[key] = module[key];`)
@@ -172,7 +172,7 @@ class SystemLibraryPlugin extends AbstractLibraryPlugin {
 										} else {
 											instructions.push(
 												Template.asString([
-													"Object.keys(module).forEach(function(key) {",
+													"Object.keys(module).forEach((key) => {",
 													Template.indent([`${external}[key] = module[key];`]),
 													"});"
 												])
diff --git a/lib/library/UmdLibraryPlugin.js b/lib/library/UmdLibraryPlugin.js
index e0269e02713..b7489a1c0ae 100644
--- a/lib/library/UmdLibraryPlugin.js
+++ b/lib/library/UmdLibraryPlugin.js
@@ -332,11 +332,11 @@ class UmdLibraryPlugin extends AbstractLibraryPlugin {
 								)} = factory(${externalsRootArray(externals)});\n`
 							: `	else {\n${
 									externals.length > 0
-										? `		var a = typeof exports === 'object' ? factory(${externalsRequireArray(
+										? `		const a = typeof exports === 'object' ? factory(${externalsRequireArray(
 												"commonjs"
 											)}) : factory(${externalsRootArray(externals)});\n`
-										: "		var a = factory();\n"
-								}		for(var i in a) (typeof exports === 'object' ? exports : root)[i] = a[i];\n` +
+										: "		const a = factory();\n"
+								}		for(const i in a) (typeof exports === 'object' ? exports : root)[i] = a[i];\n` +
 								"	}\n"
 					}})(${runtimeTemplate.outputOptions.globalObject}, ${
 						runtimeTemplate.supportsArrowFunction()
diff --git a/lib/node/ReadFileChunkLoadingRuntimeModule.js b/lib/node/ReadFileChunkLoadingRuntimeModule.js
index f4e82e4232e..fd7da487b38 100644
--- a/lib/node/ReadFileChunkLoadingRuntimeModule.js
+++ b/lib/node/ReadFileChunkLoadingRuntimeModule.js
@@ -170,10 +170,10 @@ class ReadFileChunkLoadingRuntimeModule extends RuntimeModule {
 												: `if(${hasJsMatcher("chunkId")}) {`,
 											Template.indent([
 												"// load the chunk and return promise to it",
-												"var promise = new Promise(function(resolve, reject) {",
+												"const promise = new Promise((resolve, reject) => {",
 												Template.indent([
 													"installedChunkData = installedChunks[chunkId] = [resolve, reject];",
-													`var filename = require(${runtimeTemplate.renderNodePrefixForCoreModule("path")}).join(__dirname, ${JSON.stringify(
+													`const filename = require(${runtimeTemplate.renderNodePrefixForCoreModule("path")}).join(__dirname, ${JSON.stringify(
 														rootOutputDir
 													)} + ${
 														RuntimeGlobals.getChunkScriptFilename
@@ -215,9 +215,9 @@ class ReadFileChunkLoadingRuntimeModule extends RuntimeModule {
 				? Template.asString([
 						"function loadUpdateChunk(chunkId, updatedModulesList) {",
 						Template.indent([
-							"return new Promise(function(resolve, reject) {",
+							"return new Promise((resolve, reject) => {",
 							Template.indent([
-								`var filename = require(${runtimeTemplate.renderNodePrefixForCoreModule("path")}).join(__dirname, ${JSON.stringify(
+								`const filename = require(${runtimeTemplate.renderNodePrefixForCoreModule("path")}).join(__dirname, ${JSON.stringify(
 									rootOutputDir
 								)} + ${RuntimeGlobals.getChunkUpdateScriptFilename}(chunkId));`,
 								`require(${runtimeTemplate.renderNodePrefixForCoreModule("fs")}).readFile(filename, 'utf-8', function(err, content) {`,
@@ -255,9 +255,9 @@ class ReadFileChunkLoadingRuntimeModule extends RuntimeModule {
 				? Template.asString([
 						`${RuntimeGlobals.hmrDownloadManifest} = function() {`,
 						Template.indent([
-							"return new Promise(function(resolve, reject) {",
+							"return new Promise((resolve, reject) => {",
 							Template.indent([
-								`var filename = require(${runtimeTemplate.renderNodePrefixForCoreModule("path")}).join(__dirname, ${JSON.stringify(
+								`const filename = require(${runtimeTemplate.renderNodePrefixForCoreModule("path")}).join(__dirname, ${JSON.stringify(
 									rootOutputDir
 								)} + ${RuntimeGlobals.getUpdateManifestFilename}());`,
 								`require(${runtimeTemplate.renderNodePrefixForCoreModule("fs")}).readFile(filename, 'utf-8', function(err, content) {`,
diff --git a/lib/node/ReadFileCompileAsyncWasmPlugin.js b/lib/node/ReadFileCompileAsyncWasmPlugin.js
index bf8f273d813..8b5741d1e1b 100644
--- a/lib/node/ReadFileCompileAsyncWasmPlugin.js
+++ b/lib/node/ReadFileCompileAsyncWasmPlugin.js
@@ -72,7 +72,7 @@ class ReadFileCompileAsyncWasmPlugin {
 						])
 				: (path) =>
 						Template.asString([
-							"new Promise(function (resolve, reject) {",
+							"new Promise((resolve, reject) => {",
 							Template.indent([
 								"try {",
 								Template.indent([
diff --git a/lib/node/ReadFileCompileWasmPlugin.js b/lib/node/ReadFileCompileWasmPlugin.js
index bbc1f4dd7de..e3ee864f430 100644
--- a/lib/node/ReadFileCompileWasmPlugin.js
+++ b/lib/node/ReadFileCompileWasmPlugin.js
@@ -75,7 +75,7 @@ class ReadFileCompileWasmPlugin {
 						])
 				: (path) =>
 						Template.asString([
-							"new Promise(function (resolve, reject) {",
+							"new Promise((resolve, reject) => {",
 							Template.indent([
 								`var { readFile } = require(${compilation.runtimeTemplate.renderNodePrefixForCoreModule("fs")});`,
 								`var { join } = require(${compilation.runtimeTemplate.renderNodePrefixForCoreModule("path")});`,
diff --git a/lib/node/RequireChunkLoadingRuntimeModule.js b/lib/node/RequireChunkLoadingRuntimeModule.js
index e748a8cee03..9f6cdb48966 100644
--- a/lib/node/RequireChunkLoadingRuntimeModule.js
+++ b/lib/node/RequireChunkLoadingRuntimeModule.js
@@ -127,8 +127,8 @@ class RequireChunkLoadingRuntimeModule extends RuntimeModule {
 			"",
 			withLoading || withExternalInstallChunk
 				? `var installChunk = ${runtimeTemplate.basicFunction("chunk", [
-						"var moreModules = chunk.modules, chunkIds = chunk.ids, runtime = chunk.runtime;",
-						"for(var moduleId in moreModules) {",
+						"const moreModules = chunk.modules, chunkIds = chunk.ids, runtime = chunk.runtime;",
+						"for(const moduleId in moreModules) {",
 						Template.indent([
 							`if(${RuntimeGlobals.hasOwnProperty}(moreModules, moduleId)) {`,
 							Template.indent([
@@ -138,7 +138,7 @@ class RequireChunkLoadingRuntimeModule extends RuntimeModule {
 						]),
 						"}",
 						`if(runtime) runtime(${RuntimeGlobals.require});`,
-						"for(var i = 0; i < chunkIds.length; i++)",
+						"for(let i = 0; i < chunkIds.length; i++)",
 						Template.indent("installedChunks[chunkIds[i]] = 1;"),
 						withOnChunkLoad ? `${RuntimeGlobals.onChunksLoaded}();` : ""
 					])};`
@@ -193,9 +193,9 @@ class RequireChunkLoadingRuntimeModule extends RuntimeModule {
 							`var update = require(${JSON.stringify(rootOutputDir)} + ${
 								RuntimeGlobals.getChunkUpdateScriptFilename
 							}(chunkId));`,
-							"var updatedModules = update.modules;",
-							"var runtime = update.runtime;",
-							"for(var moduleId in updatedModules) {",
+							"const updatedModules = update.modules;",
+							"const runtime = update.runtime;",
+							"for(const moduleId in updatedModules) {",
 							Template.indent([
 								`if(${RuntimeGlobals.hasOwnProperty}(updatedModules, moduleId)) {`,
 								Template.indent([
diff --git a/lib/prefetch/ChunkPrefetchTriggerRuntimeModule.js b/lib/prefetch/ChunkPrefetchTriggerRuntimeModule.js
index 12f53e16add..c8135235f09 100644
--- a/lib/prefetch/ChunkPrefetchTriggerRuntimeModule.js
+++ b/lib/prefetch/ChunkPrefetchTriggerRuntimeModule.js
@@ -28,12 +28,12 @@ class ChunkPrefetchTriggerRuntimeModule extends RuntimeModule {
 		const compilation = /** @type {Compilation} */ (this.compilation);
 		const { runtimeTemplate } = compilation;
 		const body = [
-			"var chunks = chunkToChildrenMap[chunkId];",
+			"const chunks = chunkToChildrenMap[chunkId];",
 			`Array.isArray(chunks) && chunks.map(${RuntimeGlobals.prefetchChunk});`
 		];
 		return Template.asString([
 			Template.asString([
-				`var chunkToChildrenMap = ${JSON.stringify(chunkMap, null, "\t")};`,
+				`const chunkToChildrenMap = ${JSON.stringify(chunkMap, null, "\t")};`,
 				`${
 					RuntimeGlobals.ensureChunkHandlers
 				}.prefetch = ${runtimeTemplate.expressionFunction(
diff --git a/lib/prefetch/ChunkPreloadTriggerRuntimeModule.js b/lib/prefetch/ChunkPreloadTriggerRuntimeModule.js
index 311fc9a4910..0854f8d9bf3 100644
--- a/lib/prefetch/ChunkPreloadTriggerRuntimeModule.js
+++ b/lib/prefetch/ChunkPreloadTriggerRuntimeModule.js
@@ -28,12 +28,12 @@ class ChunkPreloadTriggerRuntimeModule extends RuntimeModule {
 		const compilation = /** @type {Compilation} */ (this.compilation);
 		const { runtimeTemplate } = compilation;
 		const body = [
-			"var chunks = chunkToChildrenMap[chunkId];",
+			"const chunks = chunkToChildrenMap[chunkId];",
 			`Array.isArray(chunks) && chunks.map(${RuntimeGlobals.preloadChunk});`
 		];
 		return Template.asString([
 			Template.asString([
-				`var chunkToChildrenMap = ${JSON.stringify(chunkMap, null, "\t")};`,
+				`const chunkToChildrenMap = ${JSON.stringify(chunkMap, null, "\t")};`,
 				`${
 					RuntimeGlobals.ensureChunkHandlers
 				}.preload = ${runtimeTemplate.basicFunction("chunkId", body)};`
diff --git a/lib/runtime/AsyncModuleRuntimeModule.js b/lib/runtime/AsyncModuleRuntimeModule.js
index 441480ba088..bfc6731a96c 100644
--- a/lib/runtime/AsyncModuleRuntimeModule.js
+++ b/lib/runtime/AsyncModuleRuntimeModule.js
@@ -28,19 +28,19 @@ class AsyncModuleRuntimeModule extends HelperRuntimeModule {
 		const fn = RuntimeGlobals.asyncModule;
 		const defer = this._deferInterop;
 		return Template.asString([
-			'var hasSymbol = typeof Symbol === "function";',
-			'var webpackQueues = hasSymbol ? Symbol("webpack queues") : "__webpack_queues__";',
-			`var webpackExports = ${
+			'const hasSymbol = typeof Symbol === "function";',
+			'const webpackQueues = hasSymbol ? Symbol("webpack queues") : "__webpack_queues__";',
+			`const webpackExports = ${
 				defer ? `${RuntimeGlobals.asyncModuleExportSymbol}= ` : ""
 			}hasSymbol ? Symbol("webpack exports") : "${RuntimeGlobals.exports}";`,
-			'var webpackError = hasSymbol ? Symbol("webpack error") : "__webpack_error__";',
+			'const webpackError = hasSymbol ? Symbol("webpack error") : "__webpack_error__";',
 			defer
-				? `var webpackDone = ${RuntimeGlobals.asyncModuleDoneSymbol} = hasSymbol ? Symbol("webpack done") : "__webpack_done__";`
+				? `const webpackDone = ${RuntimeGlobals.asyncModuleDoneSymbol} = hasSymbol ? Symbol("webpack done") : "__webpack_done__";`
 				: "",
 			defer
-				? `var webpackDefer = ${RuntimeGlobals.makeDeferredNamespaceObjectSymbol} = hasSymbol ? Symbol("webpack defer") : "__webpack_defer__";`
+				? `const webpackDefer = ${RuntimeGlobals.makeDeferredNamespaceObjectSymbol} = hasSymbol ? Symbol("webpack defer") : "__webpack_defer__";`
 				: "",
-			`var resolveQueue = ${runtimeTemplate.basicFunction("queue", [
+			`const resolveQueue = ${runtimeTemplate.basicFunction("queue", [
 				"if(queue && queue.d < 1) {",
 				Template.indent([
 					"queue.d = 1;",
@@ -55,7 +55,7 @@ class AsyncModuleRuntimeModule extends HelperRuntimeModule {
 				]),
 				"}"
 			])}`,
-			`var wrapDeps = ${runtimeTemplate.returningFunction(
+			`const wrapDeps = ${runtimeTemplate.returningFunction(
 				`deps.map(${runtimeTemplate.basicFunction("dep", [
 					'if(dep !== null && typeof dep === "object") {',
 					Template.indent([
@@ -63,17 +63,17 @@ class AsyncModuleRuntimeModule extends HelperRuntimeModule {
 							? Template.asString([
 									"if(!dep[webpackQueues] && dep[webpackDefer]) {",
 									Template.indent([
-										"var asyncDeps = dep[webpackDefer];",
-										`var hasUnresolvedAsyncSubgraph = asyncDeps.some(${runtimeTemplate.basicFunction(
+										"const asyncDeps = dep[webpackDefer];",
+										`const hasUnresolvedAsyncSubgraph = asyncDeps.some(${runtimeTemplate.basicFunction(
 											"id",
 											[
-												"var cache = __webpack_module_cache__[id];",
+												"const cache = __webpack_module_cache__[id];",
 												"return !cache || cache[webpackDone] === false;"
 											]
 										)});`,
 										"if (hasUnresolvedAsyncSubgraph) {",
 										Template.indent([
-											"var d = dep;",
+											"const d = dep;",
 											"dep = {",
 											Template.indent([
 												"then(callback) {",
@@ -95,7 +95,7 @@ class AsyncModuleRuntimeModule extends HelperRuntimeModule {
 						"if(dep[webpackQueues]) return dep;",
 						"if(dep.then) {",
 						Template.indent([
-							"var queue = [];",
+							"const queue = [];",
 							"queue.d = 0;",
 							`dep.then(${runtimeTemplate.basicFunction("r", [
 								"obj[webpackExports] = r;",
@@ -104,7 +104,7 @@ class AsyncModuleRuntimeModule extends HelperRuntimeModule {
 								"obj[webpackError] = e;",
 								"resolveQueue(queue);"
 							])});`,
-							"var obj = {};",
+							"const obj = {};",
 							defer ? "obj[webpackDefer] = false;" : "",
 							`obj[webpackQueues] = ${runtimeTemplate.expressionFunction(
 								"fn(queue)",
@@ -115,7 +115,7 @@ class AsyncModuleRuntimeModule extends HelperRuntimeModule {
 						"}"
 					]),
 					"}",
-					"var ret = {};",
+					"const ret = {};",
 					`ret[webpackQueues] = ${runtimeTemplate.emptyFunction()};`,
 					"ret[webpackExports] = dep;",
 					"return ret;"
@@ -125,12 +125,12 @@ class AsyncModuleRuntimeModule extends HelperRuntimeModule {
 			`${fn} = ${runtimeTemplate.basicFunction("module, body, hasAwait", [
 				"var queue;",
 				"hasAwait && ((queue = []).d = -1);",
-				"var depQueues = new Set();",
-				"var exports = module.exports;",
-				"var currentDeps;",
-				"var outerResolve;",
-				"var reject;",
-				`var promise = new Promise(${runtimeTemplate.basicFunction(
+				"const depQueues = new Set();",
+				"const exports = module.exports;",
+				"let currentDeps;",
+				"let outerResolve;",
+				"let reject;",
+				`const promise = new Promise(${runtimeTemplate.basicFunction(
 					"resolve, rej",
 					["reject = rej;", "outerResolve = resolve;"]
 				)});`,
@@ -150,7 +150,7 @@ class AsyncModuleRuntimeModule extends HelperRuntimeModule {
 							"return d[webpackExports];"
 						])})`
 					)}`,
-					`var promise = new Promise(${runtimeTemplate.basicFunction(
+					`const promise = new Promise(${runtimeTemplate.basicFunction(
 						"resolve",
 						[
 							`fn = ${runtimeTemplate.expressionFunction(
diff --git a/lib/runtime/AutoPublicPathRuntimeModule.js b/lib/runtime/AutoPublicPathRuntimeModule.js
index 0433194fb09..62b807bf5bb 100644
--- a/lib/runtime/AutoPublicPathRuntimeModule.js
+++ b/lib/runtime/AutoPublicPathRuntimeModule.js
@@ -47,7 +47,7 @@ class AutoPublicPathRuntimeModule extends RuntimeModule {
 				? `if (typeof ${importMetaName}.url === "string") scriptUrl = ${importMetaName}.url`
 				: Template.asString([
 						`if (${RuntimeGlobals.global}.importScripts) scriptUrl = ${RuntimeGlobals.global}.location + "";`,
-						`var document = ${RuntimeGlobals.global}.document;`,
+						`const document = ${RuntimeGlobals.global}.document;`,
 						"if (!scriptUrl && document) {",
 						Template.indent([
 							// Technically we could use `document.currentScript instanceof window.HTMLScriptElement`,
@@ -57,10 +57,10 @@ class AutoPublicPathRuntimeModule extends RuntimeModule {
 							Template.indent("scriptUrl = document.currentScript.src;"),
 							"if (!scriptUrl) {",
 							Template.indent([
-								'var scripts = document.getElementsByTagName("script");',
+								'const scripts = document.getElementsByTagName("script");',
 								"if(scripts.length) {",
 								Template.indent([
-									"var i = scripts.length - 1;",
+									"let i = scripts.length - 1;",
 									"while (i > -1 && (!scriptUrl || !/^http(s?):/.test(scriptUrl))) scriptUrl = scripts[i--].src;"
 								]),
 								"}"
diff --git a/lib/runtime/CreateFakeNamespaceObjectRuntimeModule.js b/lib/runtime/CreateFakeNamespaceObjectRuntimeModule.js
index b5f09df7952..18ba240ddb5 100644
--- a/lib/runtime/CreateFakeNamespaceObjectRuntimeModule.js
+++ b/lib/runtime/CreateFakeNamespaceObjectRuntimeModule.js
@@ -45,11 +45,11 @@ class CreateFakeNamespaceObjectRuntimeModule extends HelperRuntimeModule {
 					"if((mode & 16) && typeof value.then === 'function') return value;"
 				]),
 				"}",
-				"var ns = Object.create(null);",
+				"const ns = Object.create(null);",
 				`${RuntimeGlobals.makeNamespaceObject}(ns);`,
-				"var def = {};",
+				"const def = {};",
 				"leafPrototypes = leafPrototypes || [null, getProto({}), getProto([]), getProto(getProto)];",
-				"for(var current = mode & 2 && value; (typeof current == 'object' || typeof current == 'function') && !~leafPrototypes.indexOf(current); current = getProto(current)) {",
+				"for(let current = mode & 2 && value; (typeof current == 'object' || typeof current == 'function') && !~leafPrototypes.indexOf(current); current = getProto(current)) {",
 				Template.indent([
 					`Object.getOwnPropertyNames(current).forEach(${runtimeTemplate.expressionFunction(
 						`def[key] = ${runtimeTemplate.returningFunction("value[key]", "")}`,
diff --git a/lib/runtime/LoadScriptRuntimeModule.js b/lib/runtime/LoadScriptRuntimeModule.js
index 57df714069d..5854ad9afe9 100644
--- a/lib/runtime/LoadScriptRuntimeModule.js
+++ b/lib/runtime/LoadScriptRuntimeModule.js
@@ -109,9 +109,9 @@ class LoadScriptRuntimeModule extends HelperRuntimeModule {
 		]);
 
 		return Template.asString([
-			"var inProgress = {};",
+			"const inProgress = {};",
 			uniqueName
-				? `var dataWebpackPrefix = ${JSON.stringify(`${uniqueName}:`)};`
+				? `const dataWebpackPrefix = ${JSON.stringify(`${uniqueName}:`)};`
 				: "// data-webpack is not used as build has no uniqueName",
 			"// loadScript function to load a script via script tag",
 			`${fn} = ${runtimeTemplate.basicFunction(
@@ -120,13 +120,13 @@ class LoadScriptRuntimeModule extends HelperRuntimeModule {
 				}`,
 				[
 					"if(inProgress[url]) { inProgress[url].push(done); return; }",
-					"var script, needAttach;",
+					"let script, needAttach;",
 					"if(key !== undefined) {",
 					Template.indent([
-						'var scripts = document.getElementsByTagName("script");',
-						"for(var i = 0; i < scripts.length; i++) {",
+						'const scripts = document.getElementsByTagName("script");',
+						"for(let i = 0; i < scripts.length; i++) {",
 						Template.indent([
-							"var s = scripts[i];",
+							"const s = scripts[i];",
 							`if(s.getAttribute("src") == url${
 								uniqueName
 									? ' || s.getAttribute("data-webpack") == dataWebpackPrefix + key'
@@ -149,7 +149,7 @@ class LoadScriptRuntimeModule extends HelperRuntimeModule {
 							"// avoid mem leaks in IE.",
 							"script.onerror = script.onload = null;",
 							"clearTimeout(timeout);",
-							"var doneFns = inProgress[url];",
+							"const doneFns = inProgress[url];",
 							"delete inProgress[url];",
 							"script.parentNode && script.parentNode.removeChild(script);",
 							`doneFns && doneFns.forEach(${runtimeTemplate.returningFunction(
@@ -159,7 +159,7 @@ class LoadScriptRuntimeModule extends HelperRuntimeModule {
 							"if(prev) return prev(event);"
 						])
 					)}`,
-					`var timeout = setTimeout(onScriptComplete.bind(null, undefined, { type: 'timeout', target: script }), ${loadTimeout});`,
+					`const timeout = setTimeout(onScriptComplete.bind(null, undefined, { type: 'timeout', target: script }), ${loadTimeout});`,
 					"script.onerror = onScriptComplete.bind(null, script.onerror);",
 					"script.onload = onScriptComplete.bind(null, script.onload);",
 					"needAttach && document.head.appendChild(script);"
diff --git a/lib/runtime/MakeDeferredNamespaceObjectRuntime.js b/lib/runtime/MakeDeferredNamespaceObjectRuntime.js
index b1d91e422fd..b05c7477cc8 100644
--- a/lib/runtime/MakeDeferredNamespaceObjectRuntime.js
+++ b/lib/runtime/MakeDeferredNamespaceObjectRuntime.js
@@ -43,7 +43,7 @@ function getOptimizedDeferredModule(
 		// we can also do this if exportsType is "dynamic" and there is a "__esModule" property on it.
 		exportsType === "namespace" || exportsType === "dynamic"
 			? Template.indent([
-					`var exports = ${init};`,
+					`const exports = ${init};`,
 					`${
 						exportsType === "dynamic" ? "if (exports.__esModule) " : ""
 					}Object.defineProperty(this, "a", { value: exports });`,
@@ -63,7 +63,7 @@ function getOptimizedDeferredModule(
 const strictModuleCache = [
 	"if (cachedModule && cachedModule.error === undefined) {",
 	Template.indent([
-		"var exports = cachedModule.exports;",
+		"const exports = cachedModule.exports;",
 		"if (mode == 0) return exports;",
 		`if (mode == 1) return ${RuntimeGlobals.createFakeNamespaceObject}(exports);`,
 		`if (mode == 2) return ${RuntimeGlobals.createFakeNamespaceObject}(exports, 2);`,
@@ -103,7 +103,7 @@ class MakeDeferredNamespaceObjectRuntimeModule extends HelperRuntimeModule {
 			"// mode: 2 => default-with-named (esm-cjs compat)",
 			"// mode: 3 => dynamic (if exports has __esModule, then esm, otherwise default-with-named)",
 			"",
-			"var cachedModule = __webpack_module_cache__[moduleId];",
+			"const cachedModule = __webpack_module_cache__[moduleId];",
 			...(strictError ? strictModuleCache : nonStrictModuleCache),
 			"",
 			`var init = ${runtimeTemplate.basicFunction("", [
@@ -174,7 +174,7 @@ class MakeDeferredNamespaceObjectRuntimeModule extends HelperRuntimeModule {
 				])},`,
 				`ownKeys: ${runtimeTemplate.basicFunction("", [
 					init,
-					`var keys = Reflect.ownKeys(ns).filter(${runtimeTemplate.expressionFunction('x !== "then"', "x")}).concat([Symbol.toStringTag]);`,
+					`const keys = Reflect.ownKeys(ns).filter(${runtimeTemplate.expressionFunction('x !== "then"', "x")}).concat([Symbol.toStringTag]);`,
 					"return keys;"
 				])},`,
 				`getOwnPropertyDescriptor: ${runtimeTemplate.basicFunction("_, name", [
@@ -186,7 +186,7 @@ class MakeDeferredNamespaceObjectRuntimeModule extends HelperRuntimeModule {
 					]),
 					"}",
 					init,
-					"var desc = Reflect.getOwnPropertyDescriptor(ns, name);",
+					"const desc = Reflect.getOwnPropertyDescriptor(ns, name);",
 					'if (mode == 2 && name == "default" && !desc) {',
 					Template.indent("desc = { value: ns, configurable: true };"),
 					"}",
diff --git a/lib/runtime/RelativeUrlRuntimeModule.js b/lib/runtime/RelativeUrlRuntimeModule.js
index 92e32daed98..363d38511f2 100644
--- a/lib/runtime/RelativeUrlRuntimeModule.js
+++ b/lib/runtime/RelativeUrlRuntimeModule.js
@@ -24,16 +24,16 @@ class RelativeUrlRuntimeModule extends HelperRuntimeModule {
 		return Template.asString([
 			`${RuntimeGlobals.relativeUrl} = function RelativeURL(url) {`,
 			Template.indent([
-				'var realUrl = new URL(url, "x:/");',
-				"var values = {};",
-				"for (var key in realUrl) values[key] = realUrl[key];",
+				'const realUrl = new URL(url, "x:/");',
+				"const values = {};",
+				"for (const key in realUrl) values[key] = realUrl[key];",
 				"values.href = url;",
 				'values.pathname = url.replace(/[?#].*/, "");',
 				'values.origin = values.protocol = "";',
 				`values.toString = values.toJSON = ${runtimeTemplate.returningFunction(
 					"url"
 				)};`,
-				"for (var key in values) Object.defineProperty(this, key, { enumerable: true, configurable: true, value: values[key] });"
+				"for (const key in values) Object.defineProperty(this, key, { enumerable: true, configurable: true, value: values[key] });"
 			]),
 			"};",
 			`${RuntimeGlobals.relativeUrl}.prototype = URL.prototype;`
diff --git a/lib/runtime/StartupChunkDependenciesRuntimeModule.js b/lib/runtime/StartupChunkDependenciesRuntimeModule.js
index 7ff03978353..c17e47e7245 100644
--- a/lib/runtime/StartupChunkDependenciesRuntimeModule.js
+++ b/lib/runtime/StartupChunkDependenciesRuntimeModule.js
@@ -34,7 +34,7 @@ class StartupChunkDependenciesRuntimeModule extends RuntimeModule {
 		const compilation = /** @type {Compilation} */ (this.compilation);
 		const { runtimeTemplate } = compilation;
 		return Template.asString([
-			`var next = ${RuntimeGlobals.startup};`,
+			`const next = ${RuntimeGlobals.startup};`,
 			`${RuntimeGlobals.startup} = ${runtimeTemplate.basicFunction(
 				"",
 				!this.asyncChunkLoading
diff --git a/lib/runtime/StartupEntrypointRuntimeModule.js b/lib/runtime/StartupEntrypointRuntimeModule.js
index ab36f0cec60..e20ef2fec77 100644
--- a/lib/runtime/StartupEntrypointRuntimeModule.js
+++ b/lib/runtime/StartupEntrypointRuntimeModule.js
@@ -28,7 +28,7 @@ class StartupEntrypointRuntimeModule extends RuntimeModule {
 			RuntimeGlobals.startupEntrypoint
 		} = ${runtimeTemplate.basicFunction("result, chunkIds, fn", [
 			"// arguments: chunkIds, moduleId are deprecated",
-			"var moduleId = chunkIds;",
+			"const moduleId = chunkIds;",
 			`if(!fn) chunkIds = result, fn = ${runtimeTemplate.returningFunction(
 				`${RuntimeGlobals.require}(${RuntimeGlobals.entryModuleId} = moduleId)`
 			)};`,
@@ -37,13 +37,13 @@ class StartupEntrypointRuntimeModule extends RuntimeModule {
 						`return Promise.all(chunkIds.map(${RuntimeGlobals.ensureChunk}, ${
 							RuntimeGlobals.require
 						})).then(${runtimeTemplate.basicFunction("", [
-							"var r = fn();",
+							"const r = fn();",
 							"return r === undefined ? result : r;"
 						])})`
 					]
 				: [
 						`chunkIds.map(${RuntimeGlobals.ensureChunk}, ${RuntimeGlobals.require})`,
-						"var r = fn();",
+						"const r = fn();",
 						"return r === undefined ? result : r;"
 					])
 		])}`;
diff --git a/lib/sharing/ConsumeSharedRuntimeModule.js b/lib/sharing/ConsumeSharedRuntimeModule.js
index 1da174b62d1..9d992fb9c4c 100644
--- a/lib/sharing/ConsumeSharedRuntimeModule.js
+++ b/lib/sharing/ConsumeSharedRuntimeModule.js
@@ -121,8 +121,8 @@ class ConsumeSharedRuntimeModule extends RuntimeModule {
 			`var findLatestVersion = ${runtimeTemplate.basicFunction(
 				"scope, key, eager",
 				[
-					"var versions = eager ? eagerOnly(scope[key]) : scope[key];",
-					`var key = Object.keys(versions).reduce(${runtimeTemplate.basicFunction(
+					"const versions = eager ? eagerOnly(scope[key]) : scope[key];",
+					`const key = Object.keys(versions).reduce(${runtimeTemplate.basicFunction(
 						"a, b",
 						["return !a || versionLt(a, b) ? b : a;"]
 					)}, 0);`,
@@ -132,8 +132,8 @@ class ConsumeSharedRuntimeModule extends RuntimeModule {
 			`var findSatisfyingVersion = ${runtimeTemplate.basicFunction(
 				"scope, key, requiredVersion, eager",
 				[
-					"var versions = eager ? eagerOnly(scope[key]) : scope[key];",
-					`var key = Object.keys(versions).reduce(${runtimeTemplate.basicFunction(
+					"const versions = eager ? eagerOnly(scope[key]) : scope[key];",
+					`const key = Object.keys(versions).reduce(${runtimeTemplate.basicFunction(
 						"a, b",
 						[
 							"if (!satisfy(requiredVersion, b)) return a;",
@@ -146,7 +146,7 @@ class ConsumeSharedRuntimeModule extends RuntimeModule {
 			`var findSingletonVersionKey = ${runtimeTemplate.basicFunction(
 				"scope, key, eager",
 				[
-					"var versions = eager ? eagerOnly(scope[key]) : scope[key];",
+					"const versions = eager ? eagerOnly(scope[key]) : scope[key];",
 					`return Object.keys(versions).reduce(${runtimeTemplate.basicFunction(
 						"a, b",
 						["return !a || (!versions[a].loaded && versionLt(a, b)) ? b : a;"]
@@ -162,7 +162,7 @@ class ConsumeSharedRuntimeModule extends RuntimeModule {
 			`var getInvalidVersionMessage = ${runtimeTemplate.basicFunction(
 				"scope, scopeName, key, requiredVersion, eager",
 				[
-					"var versions = scope[key];",
+					"const versions = scope[key];",
 					'return "No satisfying version (" + rangeToString(requiredVersion) + ")" + (eager ? " for eager consumption" : "") + " of shared module " + key + " found in shared scope " + scopeName + ".\\n" +',
 					`\t"Available versions: " + Object.keys(versions).map(${runtimeTemplate.basicFunction(
 						"key",
@@ -187,7 +187,7 @@ class ConsumeSharedRuntimeModule extends RuntimeModule {
 				Template.asString([
 					"function(scopeName, key, eager, c, d) {",
 					Template.indent([
-						`var promise = ${RuntimeGlobals.initializeSharing}(scopeName);`,
+						`const promise = ${RuntimeGlobals.initializeSharing}(scopeName);`,
 						// if we require eager shared, we expect it to be already loaded before it requested, no need to wait the whole scope loaded.
 						"if (promise && promise.then && !eager) { ",
 						Template.indent([
@@ -216,7 +216,7 @@ class ConsumeSharedRuntimeModule extends RuntimeModule {
 				"scopeName, scope, key, eager, requiredVersion, fallback",
 				[
 					"if (!exists(scope, key)) return useFallback(scopeName, key, fallback);",
-					"var satisfyingVersion = findSatisfyingVersion(scope, key, requiredVersion, eager);",
+					"const satisfyingVersion = findSatisfyingVersion(scope, key, requiredVersion, eager);",
 					"if (satisfyingVersion) return get(satisfyingVersion);",
 					"warn(getInvalidVersionMessage(scope, scopeName, key, requiredVersion, eager))",
 					"return get(findLatestVersion(scope, key, eager));"
@@ -226,7 +226,7 @@ class ConsumeSharedRuntimeModule extends RuntimeModule {
 				"scopeName, scope, key, eager, requiredVersion, fallback",
 				[
 					"if (!exists(scope, key)) return useFallback(scopeName, key, fallback);",
-					"var satisfyingVersion = findSatisfyingVersion(scope, key, requiredVersion, eager);",
+					"const satisfyingVersion = findSatisfyingVersion(scope, key, requiredVersion, eager);",
 					"if (satisfyingVersion) return get(satisfyingVersion);",
 					"if (fallback) return fallback();",
 					"fail(getInvalidVersionMessage(scope, scopeName, key, requiredVersion, eager));"
@@ -236,7 +236,7 @@ class ConsumeSharedRuntimeModule extends RuntimeModule {
 				"scopeName, scope, key, eager, fallback",
 				[
 					"if (!exists(scope, key)) return useFallback(scopeName, key, fallback);",
-					"var version = findSingletonVersionKey(scope, key, eager);",
+					"const version = findSingletonVersionKey(scope, key, eager);",
 					"return get(scope[key][version]);"
 				]
 			)});`,
@@ -244,7 +244,7 @@ class ConsumeSharedRuntimeModule extends RuntimeModule {
 				"scopeName, scope, key, eager, requiredVersion, fallback",
 				[
 					"if (!exists(scope, key)) return useFallback(scopeName, key, fallback);",
-					"var version = findSingletonVersionKey(scope, key, eager);",
+					"const version = findSingletonVersionKey(scope, key, eager);",
 					"if (!satisfy(requiredVersion, version)) {",
 					Template.indent([
 						"warn(getInvalidSingletonVersionMessage(scope, key, version, requiredVersion));"
@@ -257,7 +257,7 @@ class ConsumeSharedRuntimeModule extends RuntimeModule {
 				"scopeName, scope, key, eager, requiredVersion, fallback",
 				[
 					"if (!exists(scope, key)) return useFallback(scopeName, key, fallback);",
-					"var version = findSingletonVersionKey(scope, key, eager);",
+					"const version = findSingletonVersionKey(scope, key, eager);",
 					"if (!satisfy(requiredVersion, version)) {",
 					Template.indent([
 						"fail(getInvalidSingletonVersionMessage(scope, key, version, requiredVersion));"
@@ -266,7 +266,7 @@ class ConsumeSharedRuntimeModule extends RuntimeModule {
 					"return get(scope[key][version]);"
 				]
 			)});`,
-			"var installedModules = {};",
+			"const installedModules = {};",
 			"var moduleToHandlerMapping = {",
 			Template.indent(
 				Array.from(
@@ -278,7 +278,7 @@ class ConsumeSharedRuntimeModule extends RuntimeModule {
 
 			initialConsumes.length > 0
 				? Template.asString([
-						`var initialConsumes = ${JSON.stringify(initialConsumes)};`,
+						`const initialConsumes = ${JSON.stringify(initialConsumes)};`,
 						`initialConsumes.forEach(${runtimeTemplate.basicFunction("id", [
 							`${
 								RuntimeGlobals.moduleFactories
@@ -286,7 +286,7 @@ class ConsumeSharedRuntimeModule extends RuntimeModule {
 								"// Handle case when module is used sync",
 								"installedModules[id] = 0;",
 								`delete ${RuntimeGlobals.moduleCache}[id];`,
-								"var factory = moduleToHandlerMapping[id]();",
+								"const factory = moduleToHandlerMapping[id]();",
 								'if(typeof factory !== "function") throw new Error("Shared module is not available for eager consumption: " + id);',
 								"module.exports = factory();"
 							])}`
@@ -300,7 +300,7 @@ class ConsumeSharedRuntimeModule extends RuntimeModule {
 							null,
 							"\t"
 						)};`,
-						"var startedInstallModules = {};",
+						"const startedInstallModules = {};",
 						`${
 							RuntimeGlobals.ensureChunkHandlers
 						}.consumes = ${runtimeTemplate.basicFunction("chunkId, promises", [
@@ -335,7 +335,7 @@ class ConsumeSharedRuntimeModule extends RuntimeModule {
 										])};`,
 										"try {",
 										Template.indent([
-											"var promise = moduleToHandlerMapping[id]();",
+											"const promise = moduleToHandlerMapping[id]();",
 											"if(promise.then) {",
 											Template.indent(
 												"promises.push(installedModules[id] = promise.then(onFactory)['catch'](onError));"
diff --git a/lib/sharing/ShareRuntimeModule.js b/lib/sharing/ShareRuntimeModule.js
index 3e8d524d32c..a1918fca552 100644
--- a/lib/sharing/ShareRuntimeModule.js
+++ b/lib/sharing/ShareRuntimeModule.js
@@ -70,14 +70,14 @@ class ShareRuntimeModule extends RuntimeModule {
 		}
 		return Template.asString([
 			`${RuntimeGlobals.shareScopeMap} = {};`,
-			"var initPromises = {};",
-			"var initTokens = {};",
+			"const initPromises = {};",
+			"const initTokens = {};",
 			`${RuntimeGlobals.initializeSharing} = ${runtimeTemplate.basicFunction(
 				"name, initScope",
 				[
 					"if(!initScope) initScope = [];",
 					"// handling circular init calls",
-					"var initToken = initTokens[name];",
+					"let initToken = initTokens[name];",
 					"if(!initToken) initToken = initTokens[name] = {};",
 					"if(initScope.indexOf(initToken) >= 0) return;",
 					"initScope.push(initToken);",
@@ -86,43 +86,43 @@ class ShareRuntimeModule extends RuntimeModule {
 					"// creates a new share scope if needed",
 					`if(!${RuntimeGlobals.hasOwnProperty}(${RuntimeGlobals.shareScopeMap}, name)) ${RuntimeGlobals.shareScopeMap}[name] = {};`,
 					"// runs all init snippets from all modules reachable",
-					`var scope = ${RuntimeGlobals.shareScopeMap}[name];`,
-					`var warn = ${
+					`const scope = ${RuntimeGlobals.shareScopeMap}[name];`,
+					`const warn = ${
 						ignoreBrowserWarnings
 							? runtimeTemplate.basicFunction("", "")
 							: runtimeTemplate.basicFunction("msg", [
 									'if (typeof console !== "undefined" && console.warn) console.warn(msg);'
 								])
 					};`,
-					`var uniqueName = ${JSON.stringify(uniqueName || undefined)};`,
-					`var register = ${runtimeTemplate.basicFunction(
+					`const uniqueName = ${JSON.stringify(uniqueName || undefined)};`,
+					`const register = ${runtimeTemplate.basicFunction(
 						"name, version, factory, eager",
 						[
-							"var versions = scope[name] = scope[name] || {};",
-							"var activeVersion = versions[version];",
+							"const versions = scope[name] = scope[name] || {};",
+							"const activeVersion = versions[version];",
 							"if(!activeVersion || (!activeVersion.loaded && (!eager != !activeVersion.eager ? eager : uniqueName > activeVersion.from))) versions[version] = { get: factory, from: uniqueName, eager: !!eager };"
 						]
 					)};`,
-					`var initExternal = ${runtimeTemplate.basicFunction("id", [
-						`var handleError = ${runtimeTemplate.expressionFunction(
+					`const initExternal = ${runtimeTemplate.basicFunction("id", [
+						`const handleError = ${runtimeTemplate.expressionFunction(
 							'warn("Initialization of sharing external failed: " + err)',
 							"err"
 						)};`,
 						"try {",
 						Template.indent([
-							`var module = ${RuntimeGlobals.require}(id);`,
+							`const module = ${RuntimeGlobals.require}(id);`,
 							"if(!module) return;",
-							`var initFn = ${runtimeTemplate.returningFunction(
+							`const initFn = ${runtimeTemplate.returningFunction(
 								`module && module.init && module.init(${RuntimeGlobals.shareScopeMap}[name], initScope)`,
 								"module"
 							)}`,
 							"if(module.then) return promises.push(module.then(initFn, handleError));",
-							"var initResult = initFn(module);",
+							"const initResult = initFn(module);",
 							"if(initResult && initResult.then) return promises.push(initResult['catch'](handleError));"
 						]),
 						"} catch(err) { handleError(err); }"
 					])}`,
-					"var promises = [];",
+					"const promises = [];",
 					"switch(name) {",
 					...[...initCodePerScope]
 						.sort(([a], [b]) => compareStrings(a, b))
diff --git a/lib/util/semver.js b/lib/util/semver.js
index c026651bf7c..949b58e6e0b 100644
--- a/lib/util/semver.js
+++ b/lib/util/semver.js
@@ -265,8 +265,8 @@ module.exports.parseRange = (str) => {
 			/** @type {SemVerRangeItem[][]} */
 			const items = [];
 			const r = /[-0-9A-Za-z]\s+/g;
-			var start = 0;
-			var match;
+			let start = 0;
+			let match;
 			while ((match = r.exec(str))) {
 				const end = match.index + 1;
 				items.push(
diff --git a/lib/wasm-async/AsyncWasmLoadingRuntimeModule.js b/lib/wasm-async/AsyncWasmLoadingRuntimeModule.js
index 4f683dbb46c..be352f6c008 100644
--- a/lib/wasm-async/AsyncWasmLoadingRuntimeModule.js
+++ b/lib/wasm-async/AsyncWasmLoadingRuntimeModule.js
@@ -85,8 +85,8 @@ class AsyncWasmLoadingRuntimeModule extends RuntimeModule {
 				this.generateBeforeLoadBinaryCode
 					? this.generateBeforeLoadBinaryCode(wasmModuleSrcPath)
 					: "",
-				`var req = ${loader};`,
-				`var fallback = ${runtimeTemplate.returningFunction(
+				`const req = ${loader};`,
+				`const fallback = ${runtimeTemplate.returningFunction(
 					Template.asString(["req", Template.indent(fallback)])
 				)};`,
 				concat(
diff --git a/lib/wasm-sync/WasmChunkLoadingRuntimeModule.js b/lib/wasm-sync/WasmChunkLoadingRuntimeModule.js
index 5e5eefd9be5..37e538879cb 100644
--- a/lib/wasm-sync/WasmChunkLoadingRuntimeModule.js
+++ b/lib/wasm-sync/WasmChunkLoadingRuntimeModule.js
@@ -338,20 +338,20 @@ class WasmChunkLoadingRuntimeModule extends RuntimeModule {
 			`${fn}.wasm = function(chunkId, promises) {`,
 			Template.indent([
 				"",
-				"var wasmModules = wasmModuleMap[chunkId] || [];",
+				"const wasmModules = wasmModuleMap[chunkId] || [];",
 				"",
 				"wasmModules.forEach(function(wasmModuleId, idx) {",
 				Template.indent([
-					"var installedWasmModuleData = installedWasmModules[wasmModuleId];",
+					"const installedWasmModuleData = installedWasmModules[wasmModuleId];",
 					"",
 					'// a Promise means "currently loading" or "already loaded".',
 					"if(installedWasmModuleData)",
 					Template.indent(["promises.push(installedWasmModuleData);"]),
 					"else {",
 					Template.indent([
-						"var importObject = wasmImportObjects[wasmModuleId]();",
-						`var req = ${this.generateLoadBinaryCode(wasmModuleSrcPath)};`,
-						"var promise;",
+						"const importObject = wasmImportObjects[wasmModuleId]();",
+						`const req = ${this.generateLoadBinaryCode(wasmModuleSrcPath)};`,
+						"let promise;",
 						this.supportsStreaming
 							? Template.asString([
 									"if(importObject && typeof importObject.then === 'function' && typeof WebAssembly.compileStreaming === 'function') {",
@@ -374,7 +374,7 @@ class WasmChunkLoadingRuntimeModule extends RuntimeModule {
 							: Template.asString([
 									"if(importObject && typeof importObject.then === 'function') {",
 									Template.indent([
-										"var bytesPromise = req.then(function(x) { return x.arrayBuffer(); });",
+										"const bytesPromise = req.then(function(x) { return x.arrayBuffer(); });",
 										"promise = Promise.all([",
 										Template.indent([
 											"bytesPromise.then(function(bytes) { return WebAssembly.compile(bytes); }),",
@@ -391,7 +391,7 @@ class WasmChunkLoadingRuntimeModule extends RuntimeModule {
 								]),
 						"} else {",
 						Template.indent([
-							"var bytesPromise = req.then(function(x) { return x.arrayBuffer(); });",
+							"const bytesPromise = req.then(function(x) { return x.arrayBuffer(); });",
 							"promise = bytesPromise.then(function(bytes) {",
 							Template.indent([
 								`return WebAssembly.instantiate(bytes, ${createImportObject(
diff --git a/lib/wasm-sync/WebAssemblyJavascriptGenerator.js b/lib/wasm-sync/WebAssemblyJavascriptGenerator.js
index f5615dfeeb3..353a4281584 100644
--- a/lib/wasm-sync/WebAssemblyJavascriptGenerator.js
+++ b/lib/wasm-sync/WebAssemblyJavascriptGenerator.js
@@ -190,7 +190,7 @@ class WebAssemblyJavascriptGenerator extends Generator {
 			[
 				'"use strict";',
 				"// Instantiate WebAssembly module",
-				`var wasmExports = ${RuntimeGlobals.wasmInstances}[${module.moduleArgument}.id];`,
+				`const wasmExports = ${RuntimeGlobals.wasmInstances}[${module.moduleArgument}.id];`,
 
 				exportsInfo.otherExportsInfo.getUsed(runtime) !== UsageState.Unused
 					? `${RuntimeGlobals.makeNamespaceObject}(${module.exportsArgument});`
diff --git a/lib/web/JsonpChunkLoadingRuntimeModule.js b/lib/web/JsonpChunkLoadingRuntimeModule.js
index d043dd93e8a..4fe19f20333 100644
--- a/lib/web/JsonpChunkLoadingRuntimeModule.js
+++ b/lib/web/JsonpChunkLoadingRuntimeModule.js
@@ -168,7 +168,7 @@ class JsonpChunkLoadingRuntimeModule extends RuntimeModule {
 													: `if(${hasJsMatcher("chunkId")}) {`,
 												Template.indent([
 													"// setup Promise in chunk cache",
-													`var promise = new Promise(${runtimeTemplate.expressionFunction(
+													`const promise = new Promise(${runtimeTemplate.expressionFunction(
 														"installedChunkData = installedChunks[chunkId] = [resolve, reject]",
 														"resolve, reject"
 													)});`,
@@ -177,7 +177,7 @@ class JsonpChunkLoadingRuntimeModule extends RuntimeModule {
 													"// start chunk loading",
 													`var url = ${RuntimeGlobals.publicPath} + ${RuntimeGlobals.getChunkScriptFilename}(chunkId);`,
 													"// create error before stack unwound to get useful stacktrace later",
-													"var error = new Error();",
+													"const error = new Error();",
 													`var loadingEnded = ${runtimeTemplate.basicFunction(
 														"event",
 														[
@@ -320,7 +320,7 @@ class JsonpChunkLoadingRuntimeModule extends RuntimeModule {
 									"// start update chunk loading",
 									`var url = ${RuntimeGlobals.publicPath} + ${RuntimeGlobals.getChunkUpdateScriptFilename}(chunkId);`,
 									"// create error before stack unwound to get useful stacktrace later",
-									"var error = new Error();",
+									"const error = new Error();",
 									`var loadingEnded = ${runtimeTemplate.basicFunction("event", [
 										"if(waitingUpdateResolves[chunkId]) {",
 										Template.indent([
diff --git a/lib/webworker/ImportScriptsChunkLoadingRuntimeModule.js b/lib/webworker/ImportScriptsChunkLoadingRuntimeModule.js
index 0a0699744ae..61f4a4bba55 100644
--- a/lib/webworker/ImportScriptsChunkLoadingRuntimeModule.js
+++ b/lib/webworker/ImportScriptsChunkLoadingRuntimeModule.js
@@ -165,8 +165,8 @@ class ImportScriptsChunkLoadingRuntimeModule extends RuntimeModule {
 								)};`
 							: "",
 						"",
-						`var chunkLoadingGlobal = ${chunkLoadingGlobalExpr} = ${chunkLoadingGlobalExpr} || [];`,
-						"var parentChunkLoadingFunction = chunkLoadingGlobal.push.bind(chunkLoadingGlobal);",
+						`const chunkLoadingGlobal = ${chunkLoadingGlobalExpr} = ${chunkLoadingGlobalExpr} || [];`,
+						"const parentChunkLoadingFunction = chunkLoadingGlobal.push.bind(chunkLoadingGlobal);",
 						"chunkLoadingGlobal.push = installChunk;"
 					])
 				: "// no chunk loading",
@@ -175,7 +175,7 @@ class ImportScriptsChunkLoadingRuntimeModule extends RuntimeModule {
 				? Template.asString([
 						"function loadUpdateChunk(chunkId, updatedModulesList) {",
 						Template.indent([
-							"var success = false;",
+							"let success = false;",
 							`${globalObject}[${JSON.stringify(
 								compilation.outputOptions.hotUpdateGlobal
 							)}] = ${runtimeTemplate.basicFunction("_, moreModules, runtime", [