recompile build folder with `const` over let

18 files changed, 213 insertions, 207 deletions

diff --git a/build/azure-pipelines/common/computeNodeModulesCacheKey.js b/build/azure-pipelines/common/computeNodeModulesCacheKey.js
index d15ceb6ef08..b5e293d7e64 100644
--- a/build/azure-pipelines/common/computeNodeModulesCacheKey.js
+++ b/build/azure-pipelines/common/computeNodeModulesCacheKey.js
@@ -14,7 +14,7 @@ shasum.update(fs.readFileSync(path.join(ROOT, 'build/.cachesalt')));
 shasum.update(fs.readFileSync(path.join(ROOT, '.yarnrc')));
 shasum.update(fs.readFileSync(path.join(ROOT, 'remote/.yarnrc')));
 // Add `package.json` and `yarn.lock` files
-for (let dir of dirs) {
+for (const dir of dirs) {
     const packageJsonPath = path.join(ROOT, dir, 'package.json');
     const packageJson = JSON.parse(fs.readFileSync(packageJsonPath).toString());
     const relevantPackageJsonSections = {
diff --git a/build/azure-pipelines/upload-nlsmetadata.js b/build/azure-pipelines/upload-nlsmetadata.js
index a17b8e71267..9e6776cd477 100644
--- a/build/azure-pipelines/upload-nlsmetadata.js
+++ b/build/azure-pipelines/upload-nlsmetadata.js
@@ -19,7 +19,6 @@ function main() {
             fileName: 'combined.nls.metadata.json',
             jsonSpace: '',
             edit: (parsedJson, file) => {
-                let key;
                 if (file.base === 'out-vscode-web-min') {
                     return { vscode: parsedJson };
                 }
@@ -63,7 +62,7 @@ function main() {
                         break;
                     }
                 }
-                key = 'vscode.' + file.relative.split('/')[0];
+                const key = 'vscode.' + file.relative.split('/')[0];
                 return { [key]: parsedJson };
             },
         }))
diff --git a/build/darwin/create-universal-app.js b/build/darwin/create-universal-app.js
index 197bf5b2f1b..f6ebf6f06e3 100644
--- a/build/darwin/create-universal-app.js
+++ b/build/darwin/create-universal-app.js
@@ -39,7 +39,7 @@ async function main() {
         outAppPath,
         force: true
     });
-    let productJson = await fs.readJson(productJsonPath);
+    const productJson = await fs.readJson(productJsonPath);
     Object.assign(productJson, {
         darwinUniversalAssetId: 'darwin-universal'
     });
diff --git a/build/lib/asar.js b/build/lib/asar.js
index 708005791f6..926c580eec6 100644
--- a/build/lib/asar.js
+++ b/build/lib/asar.js
@@ -81,7 +81,7 @@ function createAsar(folderPath, unpackGlobs, destFilename) {
             out.push(file.contents);
         }
     }, function () {
-        let finish = () => {
+        const finish = () => {
             {
                 const headerPickle = pickle.createEmpty();
                 headerPickle.writeString(JSON.stringify(filesystem.header));
diff --git a/build/lib/builtInExtensions.js b/build/lib/builtInExtensions.js
index 2671a5a3a6c..f38871c36d7 100644
--- a/build/lib/builtInExtensions.js
+++ b/build/lib/builtInExtensions.js
@@ -102,7 +102,7 @@ function getBuiltInExtensions() {
     const control = readControlFile();
     const streams = [];
     for (const extension of [...builtInExtensions, ...webBuiltInExtensions]) {
-        let controlState = control[extension.name] || 'marketplace';
+        const controlState = control[extension.name] || 'marketplace';
         control[extension.name] = controlState;
         streams.push(syncExtension(extension, controlState));
     }
diff --git a/build/lib/compilation.js b/build/lib/compilation.js
index db489e01f9d..8ad1af97f71 100644
--- a/build/lib/compilation.js
+++ b/build/lib/compilation.js
@@ -22,7 +22,7 @@ const watch = require('./watch');
 const reporter = (0, reporter_1.createReporter)();
 function getTypeScriptCompilerOptions(src) {
     const rootDir = path.join(__dirname, `../../${src}`);
-    let options = {};
+    const options = {};
     options.verbose = false;
     options.sourceMap = true;
     if (process.env['VSCODE_NO_SOURCEMAP']) { // To be used by developers in a hurry
@@ -80,7 +80,7 @@ function compileTask(src, out, build) {
         }
         const compile = createCompile(src, build, true);
         const srcPipe = gulp.src(`${src}/**`, { base: `${src}` });
-        let generator = new MonacoGenerator(false);
+        const generator = new MonacoGenerator(false);
         if (src === 'src') {
             generator.execute();
         }
@@ -96,7 +96,7 @@ function watchTask(out, build) {
         const compile = createCompile('src', build);
         const src = gulp.src('src/**', { base: 'src' });
         const watchSrc = watch('src/**', { base: 'src', readDelay: 200 });
-        let generator = new MonacoGenerator(true);
+        const generator = new MonacoGenerator(true);
         generator.execute();
         return watchSrc
             .pipe(generator.stream)
@@ -112,7 +112,7 @@ class MonacoGenerator {
         this._isWatch = isWatch;
         this.stream = es.through();
         this._watchedFiles = {};
-        let onWillReadFile = (moduleId, filePath) => {
+        const onWillReadFile = (moduleId, filePath) => {
             if (!this._isWatch) {
                 return;
             }
@@ -149,7 +149,7 @@ class MonacoGenerator {
         }, 20);
     }
     _run() {
-        let r = monacodts.run3(this._declarationResolver);
+        const r = monacodts.run3(this._declarationResolver);
         if (!r && !this._isWatch) {
             // The build must always be able to generate the monaco.d.ts
             throw new Error(`monaco.d.ts generation error - Cannot continue`);
diff --git a/build/lib/eslint/code-no-unexternalized-strings.js b/build/lib/eslint/code-no-unexternalized-strings.js
index b603f4d8e09..48b591f8d3d 100644
--- a/build/lib/eslint/code-no-unexternalized-strings.js
+++ b/build/lib/eslint/code-no-unexternalized-strings.js
@@ -41,7 +41,7 @@ module.exports = new (_a = class NoUnexternalizedStrings {
                     key = keyNode.value;
                 }
                 else if (keyNode.type === experimental_utils_1.AST_NODE_TYPES.ObjectExpression) {
-                    for (let property of keyNode.properties) {
+                    for (const property of keyNode.properties) {
                         if (property.type === experimental_utils_1.AST_NODE_TYPES.Property && !property.computed) {
                             if (property.key.type === experimental_utils_1.AST_NODE_TYPES.Identifier && property.key.name === 'key') {
                                 if (isStringLiteral(property.value)) {
@@ -83,7 +83,7 @@ module.exports = new (_a = class NoUnexternalizedStrings {
                     // (2)
                     // report all invalid NLS keys
                     if (!key.match(NoUnexternalizedStrings._rNlsKeys)) {
-                        for (let value of values) {
+                        for (const value of values) {
                             context.report({ loc: value.call.loc, messageId: 'badKey', data: { key } });
                         }
                     }
diff --git a/build/lib/eslint/vscode-dts-cancellation.js b/build/lib/eslint/vscode-dts-cancellation.js
index d016f0d2ebc..65b9e4c1fe1 100644
--- a/build/lib/eslint/vscode-dts-cancellation.js
+++ b/build/lib/eslint/vscode-dts-cancellation.js
@@ -16,7 +16,7 @@ module.exports = new class ApiProviderNaming {
         return {
             ['TSInterfaceDeclaration[id.name=/.+Provider/] TSMethodSignature[key.name=/^(provide|resolve).+/]']: (node) => {
                 let found = false;
-                for (let param of node.params) {
+                for (const param of node.params) {
                     if (param.type === experimental_utils_1.AST_NODE_TYPES.Identifier) {
                         found = found || param.name === 'token';
                     }
diff --git a/build/lib/extensions.js b/build/lib/extensions.js
index 50fc4dd945b..09fb5813a0a 100644
--- a/build/lib/extensions.js
+++ b/build/lib/extensions.js
@@ -345,7 +345,7 @@ function scanBuiltinExtensions(extensionsRoot, exclude = []) {
             if (!fs.existsSync(packageJSONPath)) {
                 continue;
             }
-            let packageJSON = JSON.parse(fs.readFileSync(packageJSONPath).toString('utf8'));
+            const packageJSON = JSON.parse(fs.readFileSync(packageJSONPath).toString('utf8'));
             if (!isWebExtension(packageJSON)) {
                 continue;
             }
@@ -373,7 +373,7 @@ function translatePackageJSON(packageJSON, packageNLSPath) {
     const CharCode_PC = '%'.charCodeAt(0);
     const packageNls = JSON.parse(fs.readFileSync(packageNLSPath).toString());
     const translate = (obj) => {
-        for (let key in obj) {
+        for (const key in obj) {
             const val = obj[key];
             if (Array.isArray(val)) {
                 val.forEach(translate);
diff --git a/build/lib/git.js b/build/lib/git.js
index 1726f76fcc7..7e381b76e68 100644
--- a/build/lib/git.js
+++ b/build/lib/git.js
@@ -45,7 +45,7 @@ function getVersion(repo) {
     }
     const refsRegex = /^([0-9a-f]{40})\s+(.+)$/gm;
     let refsMatch;
-    let refs = {};
+    const refs = {};
     while (refsMatch = refsRegex.exec(refsRaw)) {
         refs[refsMatch[2]] = refsMatch[1];
     }
diff --git a/build/lib/i18n.js b/build/lib/i18n.js
index e89cdf1504e..99527778da0 100644
--- a/build/lib/i18n.js
+++ b/build/lib/i18n.js
@@ -46,7 +46,7 @@ exports.externalExtensionsWithTranslations = {
 var LocalizeInfo;
 (function (LocalizeInfo) {
     function is(value) {
-        let candidate = value;
+        const candidate = value;
         return Is.defined(candidate) && Is.string(candidate.key) && (Is.undef(candidate.comment) || (Is.array(candidate.comment) && candidate.comment.every(element => Is.string(element))));
     }
     LocalizeInfo.is = is;
@@ -57,8 +57,8 @@ var BundledFormat;
         if (Is.undef(value)) {
             return false;
         }
-        let candidate = value;
-        let length = Object.keys(value).length;
+        const candidate = value;
+        const length = Object.keys(value).length;
         return length === 3 && Is.defined(candidate.keys) && Is.defined(candidate.messages) && Is.defined(candidate.bundles);
     }
     BundledFormat.is = is;
@@ -70,7 +70,7 @@ var PackageJsonFormat;
             return false;
         }
         return Object.keys(value).every(key => {
-            let element = value[key];
+            const element = value[key];
             return Is.string(element) || (Is.object(element) && Is.defined(element.message) && Is.defined(element.comment));
         });
     }
@@ -133,9 +133,9 @@ class XLF {
         }
         this.numberOfMessages += keys.length;
         this.files[original] = [];
-        let existingKeys = new Set();
+        const existingKeys = new Set();
         for (let i = 0; i < keys.length; i++) {
-            let key = keys[i];
+            const key = keys[i];
             let realKey;
             let comment;
             if (Is.string(key)) {
@@ -152,7 +152,7 @@ class XLF {
                 continue;
             }
             existingKeys.add(realKey);
-            let message = encodeEntities(messages[i]);
+            const message = encodeEntities(messages[i]);
             this.files[original].push({ id: realKey, message: message, comment: comment });
         }
     }
@@ -178,7 +178,7 @@ class XLF {
         this.appendNewLine('</xliff>', 0);
     }
     appendNewLine(content, indent) {
-        let line = new Line(indent);
+        const line = new Line(indent);
         line.append(content);
         this.buffer.push(line.toString());
     }
@@ -186,8 +186,8 @@ class XLF {
 exports.XLF = XLF;
 XLF.parsePseudo = function (xlfString) {
     return new Promise((resolve) => {
-        let parser = new xml2js.Parser();
-        let files = [];
+        const parser = new xml2js.Parser();
+        const files = [];
         parser.parseString(xlfString, function (_err, result) {
             const fileNodes = result['xliff']['file'];
             fileNodes.forEach(file => {
@@ -211,8 +211,8 @@ XLF.parsePseudo = function (xlfString) {
 };
 XLF.parse = function (xlfString) {
     return new Promise((resolve, reject) => {
-        let parser = new xml2js.Parser();
-        let files = [];
+        const parser = new xml2js.Parser();
+        const files = [];
         parser.parseString(xlfString, function (err, result) {
             if (err) {
                 reject(new Error(`XLF parsing error: Failed to parse XLIFF string. ${err}`));
@@ -226,7 +226,7 @@ XLF.parse = function (xlfString) {
                 if (!originalFilePath) {
                     reject(new Error(`XLF parsing error: XLIFF file node does not contain original attribute to determine the original location of the resource file.`));
                 }
-                let language = file.$['target-language'];
+                const language = file.$['target-language'];
                 if (!language) {
                     reject(new Error(`XLF parsing error: XLIFF file node does not contain target-language attribute to determine translated language.`));
                 }
@@ -296,7 +296,7 @@ function stripComments(content) {
     // Third group matches a multi line comment
     // Forth group matches a single line comment
     const regexp = /("[^"\\]*(?:\\.[^"\\]*)*")|('[^'\\]*(?:\\.[^'\\]*)*')|(\/\*[^\/\*]*(?:(?:\*|\/)[^\/\*]*)*?\*\/)|(\/{2,}.*?(?:(?:\r?\n)|$))/g;
-    let result = content.replace(regexp, (match, _m1, _m2, m3, m4) => {
+    const result = content.replace(regexp, (match, _m1, _m2, m3, m4) => {
         // Only one of m1, m2, m3, m4 matches
         if (m3) {
             // A block comment. Replace with nothing
@@ -356,20 +356,20 @@ function escapeCharacters(value) {
     return result.join('');
 }
 function processCoreBundleFormat(fileHeader, languages, json, emitter) {
-    let keysSection = json.keys;
-    let messageSection = json.messages;
-    let bundleSection = json.bundles;
-    let statistics = Object.create(null);
-    let defaultMessages = Object.create(null);
-    let modules = Object.keys(keysSection);
+    const keysSection = json.keys;
+    const messageSection = json.messages;
+    const bundleSection = json.bundles;
+    const statistics = Object.create(null);
+    const defaultMessages = Object.create(null);
+    const modules = Object.keys(keysSection);
     modules.forEach((module) => {
-        let keys = keysSection[module];
-        let messages = messageSection[module];
+        const keys = keysSection[module];
+        const messages = messageSection[module];
         if (!messages || keys.length !== messages.length) {
             emitter.emit('error', `Message for module ${module} corrupted. Mismatch in number of keys and messages.`);
             return;
         }
-        let messageMap = Object.create(null);
+        const messageMap = Object.create(null);
         defaultMessages[module] = messageMap;
         keys.map((key, i) => {
             if (typeof key === 'string') {
@@ -380,27 +380,27 @@ function processCoreBundleFormat(fileHeader, languages, json, emitter) {
             }
         });
     });
-    let languageDirectory = path.join(__dirname, '..', '..', '..', 'vscode-loc', 'i18n');
+    const languageDirectory = path.join(__dirname, '..', '..', '..', 'vscode-loc', 'i18n');
     if (!fs.existsSync(languageDirectory)) {
         log(`No VS Code localization repository found. Looking at ${languageDirectory}`);
         log(`To bundle translations please check out the vscode-loc repository as a sibling of the vscode repository.`);
     }
-    let sortedLanguages = sortLanguages(languages);
+    const sortedLanguages = sortLanguages(languages);
     sortedLanguages.forEach((language) => {
         if (process.env['VSCODE_BUILD_VERBOSE']) {
             log(`Generating nls bundles for: ${language.id}`);
         }
         statistics[language.id] = 0;
-        let localizedModules = Object.create(null);
-        let languageFolderName = language.translationId || language.id;
-        let i18nFile = path.join(languageDirectory, `vscode-language-pack-${languageFolderName}`, 'translations', 'main.i18n.json');
+        const localizedModules = Object.create(null);
+        const languageFolderName = language.translationId || language.id;
+        const i18nFile = path.join(languageDirectory, `vscode-language-pack-${languageFolderName}`, 'translations', 'main.i18n.json');
         let allMessages;
         if (fs.existsSync(i18nFile)) {
-            let content = stripComments(fs.readFileSync(i18nFile, 'utf8'));
+            const content = stripComments(fs.readFileSync(i18nFile, 'utf8'));
             allMessages = JSON.parse(content);
         }
         modules.forEach((module) => {
-            let order = keysSection[module];
+            const order = keysSection[module];
             let moduleMessage;
             if (allMessages) {
                 moduleMessage = allMessages.contents[module];
@@ -412,7 +412,7 @@ function processCoreBundleFormat(fileHeader, languages, json, emitter) {
                 moduleMessage = defaultMessages[module];
                 statistics[language.id] = statistics[language.id] + Object.keys(moduleMessage).length;
             }
-            let localizedMessages = [];
+            const localizedMessages = [];
             order.forEach((keyInfo) => {
                 let key = null;
                 if (typeof keyInfo === 'string') {
@@ -434,14 +434,14 @@ function processCoreBundleFormat(fileHeader, languages, json, emitter) {
             localizedModules[module] = localizedMessages;
         });
         Object.keys(bundleSection).forEach((bundle) => {
-            let modules = bundleSection[bundle];
-            let contents = [
+            const modules = bundleSection[bundle];
+            const contents = [
                 fileHeader,
                 `define("${bundle}.nls.${language.id}", {`
             ];
             modules.forEach((module, index) => {
                 contents.push(`\t"${module}": [`);
-                let messages = localizedModules[module];
+                const messages = localizedModules[module];
                 if (!messages) {
                     emitter.emit('error', `Didn't find messages for module ${module}.`);
                     return;
@@ -456,11 +456,11 @@ function processCoreBundleFormat(fileHeader, languages, json, emitter) {
         });
     });
     Object.keys(statistics).forEach(key => {
-        let value = statistics[key];
+        const value = statistics[key];
         log(`${key} has ${value} untranslated strings.`);
     });
     sortedLanguages.forEach(language => {
-        let stats = statistics[language.id];
+        const stats = statistics[language.id];
         if (Is.undef(stats)) {
             log(`\tNo translations found for language ${language.id}. Using default language instead.`);
         }
@@ -468,7 +468,7 @@ function processCoreBundleFormat(fileHeader, languages, json, emitter) {
 }
 function processNlsFiles(opts) {
     return (0, event_stream_1.through)(function (file) {
-        let fileName = path.basename(file.path);
+        const fileName = path.basename(file.path);
         if (fileName === 'nls.metadata.json') {
             let json = null;
             if (file.isBuffer()) {
@@ -525,7 +525,7 @@ function createXlfFilesForCoreBundle() {
             if (file.isBuffer()) {
                 const xlfs = Object.create(null);
                 const json = JSON.parse(file.contents.toString('utf8'));
-                for (let coreModule in json.keys) {
+                for (const coreModule in json.keys) {
                     const projectResource = getResource(coreModule);
                     const resource = projectResource.name;
                     const project = projectResource.project;
@@ -544,7 +544,7 @@ function createXlfFilesForCoreBundle() {
                         xlf.addFile(`src/${coreModule}`, keys, messages);
                     }
                 }
-                for (let resource in xlfs) {
+                for (const resource in xlfs) {
                     const xlf = xlfs[resource];
                     const filePath = `${xlf.project}/${resource.replace(/\//g, '_')}.xlf`;
                     const xlfFile = new File({
@@ -576,7 +576,7 @@ function createXlfFilesForExtensions() {
         if (!stat.isDirectory()) {
             return;
         }
-        let extensionName = path.basename(extensionFolder.path);
+        const extensionName = path.basename(extensionFolder.path);
         if (extensionName === 'node_modules') {
             return;
         }
@@ -612,7 +612,7 @@ function createXlfFilesForExtensions() {
                 else if (basename === 'nls.metadata.json') {
                     const json = JSON.parse(buffer.toString('utf8'));
                     const relPath = path.relative(`.build/extensions/${extensionName}`, path.dirname(file.path));
-                    for (let file in json) {
+                    for (const file in json) {
                         const fileContent = json[file];
                         getXlf().addFile(`extensions/${extensionName}/${relPath}/${file}`, fileContent.keys, fileContent.messages);
                     }
@@ -624,7 +624,7 @@ function createXlfFilesForExtensions() {
             }
         }, function () {
             if (_xlf) {
-                let xlfFile = new File({
+                const xlfFile = new File({
                     path: path.join(extensionsProject, extensionName + '.xlf'),
                     contents: Buffer.from(_xlf.toString(), 'utf8')
                 });
@@ -656,14 +656,14 @@ function createXlfFilesForIsl() {
         else {
             throw new Error(`Unknown input file ${file.path}`);
         }
-        let xlf = new XLF(projectName), keys = [], messages = [];
-        let model = new TextModel(file.contents.toString());
+        const xlf = new XLF(projectName), keys = [], messages = [];
+        const model = new TextModel(file.contents.toString());
         let inMessageSection = false;
         model.lines.forEach(line => {
             if (line.length === 0) {
                 return;
             }
-            let firstChar = line.charAt(0);
+            const firstChar = line.charAt(0);
             switch (firstChar) {
                 case ';':
                     // Comment line;
@@ -675,13 +675,13 @@ function createXlfFilesForIsl() {
             if (!inMessageSection) {
                 return;
             }
-            let sections = line.split('=');
+            const sections = line.split('=');
             if (sections.length !== 2) {
                 throw new Error(`Badly formatted message found: ${line}`);
             }
             else {
-                let key = sections[0];
-                let value = sections[1];
+                const key = sections[0];
+                const value = sections[1];
                 if (key.length > 0 && value.length > 0) {
                     keys.push(key);
                     messages.push(value);
@@ -698,8 +698,8 @@ function createXlfFilesForIsl() {
 }
 exports.createXlfFilesForIsl = createXlfFilesForIsl;
 function pushXlfFiles(apiHostname, username, password) {
-    let tryGetPromises = [];
-    let updateCreatePromises = [];
+    const tryGetPromises = [];
+    const updateCreatePromises = [];
     return (0, event_stream_1.through)(function (file) {
         const project = path.dirname(file.relative);
         const fileName = path.basename(file.path);
@@ -737,11 +737,11 @@ function getAllResources(project, apiHostname, username, password) {
             method: 'GET'
         };
         const request = https.request(options, (res) => {
-            let buffer = [];
+            const buffer = [];
             res.on('data', (chunk) => buffer.push(chunk));
             res.on('end', () => {
                 if (res.statusCode === 200) {
-                    let json = JSON.parse(Buffer.concat(buffer).toString());
+                    const json = JSON.parse(Buffer.concat(buffer).toString());
                     if (Array.isArray(json)) {
                         resolve(json.map(o => o.slug));
                         return;
@@ -760,7 +760,7 @@ function getAllResources(project, apiHostname, username, password) {
     });
 }
 function findObsoleteResources(apiHostname, username, password) {
-    let resourcesByProject = Object.create(null);
+    const resourcesByProject = Object.create(null);
     resourcesByProject[extensionsProject] = [].concat(exports.externalExtensionsWithTranslations); // clone
     return (0, event_stream_1.through)(function (file) {
         const project = path.dirname(file.relative);
@@ -774,10 +774,10 @@ function findObsoleteResources(apiHostname, username, password) {
         this.push(file);
     }, function () {
         const json = JSON.parse(fs.readFileSync('./build/lib/i18n.resources.json', 'utf8'));
-        let i18Resources = [...json.editor, ...json.workbench].map((r) => r.project + '/' + r.name.replace(/\//g, '_'));
-        let extractedResources = [];
-        for (let project of [workbenchProject, editorProject]) {
-            for (let resource of resourcesByProject[project]) {
+        const i18Resources = [...json.editor, ...json.workbench].map((r) => r.project + '/' + r.name.replace(/\//g, '_'));
+        const extractedResources = [];
+        for (const project of [workbenchProject, editorProject]) {
+            for (const resource of resourcesByProject[project]) {
                 if (resource !== 'setup_messages') {
                     extractedResources.push(project + '/' + resource);
                 }
@@ -787,11 +787,11 @@ function findObsoleteResources(apiHostname, username, password) {
             console.log(`[i18n] Obsolete resources in file 'build/lib/i18n.resources.json': JSON.stringify(${i18Resources.filter(p => extractedResources.indexOf(p) === -1)})`);
             console.log(`[i18n] Missing resources in file 'build/lib/i18n.resources.json': JSON.stringify(${extractedResources.filter(p => i18Resources.indexOf(p) === -1)})`);
         }
-        let promises = [];
-        for (let project in resourcesByProject) {
+        const promises = [];
+        for (const project in resourcesByProject) {
             promises.push(getAllResources(project, apiHostname, username, password).then(resources => {
-                let expectedResources = resourcesByProject[project];
-                let unusedResources = resources.filter(resource => resource && expectedResources.indexOf(resource) === -1);
+                const expectedResources = resourcesByProject[project];
+                const unusedResources = resources.filter(resource => resource && expectedResources.indexOf(resource) === -1);
                 if (unusedResources.length) {
                     console.log(`[transifex] Obsolete resources in project '${project}': ${unusedResources.join(', ')}`);
                 }
@@ -846,7 +846,7 @@ function createResource(project, slug, xlfFile, apiHostname, credentials) {
             auth: credentials,
             method: 'POST'
         };
-        let request = https.request(options, (res) => {
+        const request = https.request(options, (res) => {
             if (res.statusCode === 201) {
                 log(`Resource ${project}/${slug} successfully created on Transifex.`);
             }
@@ -878,7 +878,7 @@ function updateResource(project, slug, xlfFile, apiHostname, credentials) {
             auth: credentials,
             method: 'PUT'
         };
-        let request = https.request(options, (res) => {
+        const request = https.request(options, (res) => {
             if (res.statusCode === 200) {
                 res.setEncoding('utf8');
                 let responseBuffer = '';
@@ -903,7 +903,7 @@ function updateResource(project, slug, xlfFile, apiHostname, credentials) {
     });
 }
 function pullSetupXlfFiles(apiHostname, username, password, language, includeDefault) {
-    let setupResources = [{ name: 'setup_messages', project: workbenchProject }];
+    const setupResources = [{ name: 'setup_messages', project: workbenchProject }];
     if (includeDefault) {
         setupResources.push({ name: 'setup_default', project: setupProject });
     }
@@ -912,7 +912,7 @@ function pullSetupXlfFiles(apiHostname, username, password, language, includeDef
 exports.pullSetupXlfFiles = pullSetupXlfFiles;
 function pullXlfFiles(apiHostname, username, password, language, resources) {
     const credentials = `${username}:${password}`;
-    let expectedTranslationsCount = resources.length;
+    const expectedTranslationsCount = resources.length;
     let translationsRetrieved = 0, called = false;
     return (0, event_stream_1.readable)(function (_count, callback) {
         // Mark end of stream when all resources were retrieved
@@ -939,7 +939,7 @@ function retrieveResource(language, resource, apiHostname, credentials) {
     return limiter.queue(() => new Promise((resolve, reject) => {
         const slug = resource.name.replace(/\//g, '_');
         const project = resource.project;
-        let transifexLanguageId = language.id === 'ps' ? 'en' : language.translationId || language.id;
+        const transifexLanguageId = language.id === 'ps' ? 'en' : language.translationId || language.id;
         const options = {
             hostname: apiHostname,
             path: `/api/2/project/${project}/resource/${slug}/translation/${transifexLanguageId}?file&mode=onlyreviewed`,
@@ -948,8 +948,8 @@ function retrieveResource(language, resource, apiHostname, credentials) {
             method: 'GET'
         };
         console.log('[transifex] Fetching ' + options.path);
-        let request = https.request(options, (res) => {
-            let xlfBuffer = [];
+        const request = https.request(options, (res) => {
+            const xlfBuffer = [];
             res.on('data', (chunk) => xlfBuffer.push(chunk));
             res.on('end', () => {
                 if (res.statusCode === 200) {
@@ -971,14 +971,14 @@ function retrieveResource(language, resource, apiHostname, credentials) {
     }));
 }
 function prepareI18nFiles() {
-    let parsePromises = [];
+    const parsePromises = [];
     return (0, event_stream_1.through)(function (xlf) {
-        let stream = this;
-        let parsePromise = XLF.parse(xlf.contents.toString());
+        const stream = this;
+        const parsePromise = XLF.parse(xlf.contents.toString());
         parsePromises.push(parsePromise);
         parsePromise.then(resolvedFiles => {
             resolvedFiles.forEach(file => {
-                let translatedFile = createI18nFile(file.originalFilePath, file.messages);
+                const translatedFile = createI18nFile(file.originalFilePath, file.messages);
                 stream.queue(translatedFile);
             });
         });
@@ -990,7 +990,7 @@ function prepareI18nFiles() {
 }
 exports.prepareI18nFiles = prepareI18nFiles;
 function createI18nFile(originalFilePath, messages) {
-    let result = Object.create(null);
+    const result = Object.create(null);
     result[''] = [
         '--------------------------------------------------------------------------------------------',
         'Copyright (c) Microsoft Corporation. All rights reserved.',
@@ -998,7 +998,7 @@ function createI18nFile(originalFilePath, messages) {
         '--------------------------------------------------------------------------------------------',
         'Do not edit this file. It is machine generated.'
     ];
-    for (let key of Object.keys(messages)) {
+    for (const key of Object.keys(messages)) {
         result[key] = messages[key];
     }
     let content = JSON.stringify(result, null, '\t');
@@ -1012,16 +1012,16 @@ function createI18nFile(originalFilePath, messages) {
 }
 const i18nPackVersion = '1.0.0';
 function prepareI18nPackFiles(externalExtensions, resultingTranslationPaths, pseudo = false) {
-    let parsePromises = [];
-    let mainPack = { version: i18nPackVersion, contents: {} };
-    let extensionsPacks = {};
-    let errors = [];
+    const parsePromises = [];
+    const mainPack = { version: i18nPackVersion, contents: {} };
+    const extensionsPacks = {};
+    const errors = [];
     return (0, event_stream_1.through)(function (xlf) {
-        let project = path.basename(path.dirname(path.dirname(xlf.relative)));
-        let resource = path.basename(xlf.relative, '.xlf');
-        let contents = xlf.contents.toString();
+        const project = path.basename(path.dirname(path.dirname(xlf.relative)));
+        const resource = path.basename(xlf.relative, '.xlf');
+        const contents = xlf.contents.toString();
         log(`Found ${project}: ${resource}`);
-        let parsePromise = pseudo ? XLF.parsePseudo(contents) : XLF.parse(contents);
+        const parsePromise = pseudo ? XLF.parsePseudo(contents) : XLF.parse(contents);
         parsePromises.push(parsePromise);
         parsePromise.then(resolvedFiles => {
             resolvedFiles.forEach(file => {
@@ -1057,7 +1057,7 @@ function prepareI18nPackFiles(externalExtensions, resultingTranslationPaths, pse
             const translatedMainFile = createI18nFile('./main', mainPack);
             resultingTranslationPaths.push({ id: 'vscode', resourceName: 'main.i18n.json' });
             this.queue(translatedMainFile);
-            for (let extension in extensionsPacks) {
+            for (const extension in extensionsPacks) {
                 const translatedExtFile = createI18nFile(`extensions/${extension}`, extensionsPacks[extension]);
                 this.queue(translatedExtFile);
                 const externalExtensionId = externalExtensions[extension];
@@ -1077,14 +1077,14 @@ function prepareI18nPackFiles(externalExtensions, resultingTranslationPaths, pse
 }
 exports.prepareI18nPackFiles = prepareI18nPackFiles;
 function prepareIslFiles(language, innoSetupConfig) {
-    let parsePromises = [];
+    const parsePromises = [];
     return (0, event_stream_1.through)(function (xlf) {
-        let stream = this;
-        let parsePromise = XLF.parse(xlf.contents.toString());
+        const stream = this;
+        const parsePromise = XLF.parse(xlf.contents.toString());
         parsePromises.push(parsePromise);
         parsePromise.then(resolvedFiles => {
             resolvedFiles.forEach(file => {
-                let translatedFile = createIslFile(file.originalFilePath, file.messages, language, innoSetupConfig);
+                const translatedFile = createIslFile(file.originalFilePath, file.messages, language, innoSetupConfig);
                 stream.queue(translatedFile);
             });
         }).catch(reason => {
@@ -1100,7 +1100,7 @@ function prepareIslFiles(language, innoSetupConfig) {
 }
 exports.prepareIslFiles = prepareIslFiles;
 function createIslFile(originalFilePath, messages, language, innoSetup) {
-    let content = [];
+    const content = [];
     let originalContent;
     if (path.basename(originalFilePath) === 'Default') {
         originalContent = new TextModel(fs.readFileSync(originalFilePath + '.isl', 'utf8'));
@@ -1110,16 +1110,16 @@ function createIslFile(originalFilePath, messages, language, innoSetup) {
     }
     originalContent.lines.forEach(line => {
         if (line.length > 0) {
-            let firstChar = line.charAt(0);
+            const firstChar = line.charAt(0);
             if (firstChar === '[' || firstChar === ';') {
                 content.push(line);
             }
             else {
-                let sections = line.split('=');
-                let key = sections[0];
+                const sections = line.split('=');
+                const key = sections[0];
                 let translated = line;
                 if (key) {
-                    let translatedMessage = messages[key];
+                    const translatedMessage = messages[key];
                     if (translatedMessage) {
                         translated = `${key}=${translatedMessage}`;
                     }
@@ -1137,9 +1137,9 @@ function createIslFile(originalFilePath, messages, language, innoSetup) {
     });
 }
 function encodeEntities(value) {
-    let result = [];
+    const result = [];
     for (let i = 0; i < value.length; i++) {
-        let ch = value[i];
+        const ch = value[i];
         switch (ch) {
             case '<':
                 result.push('&lt;');
diff --git a/build/lib/monaco-api.js b/build/lib/monaco-api.js
index d708d6346b3..a7542b711df 100644
--- a/build/lib/monaco-api.js
+++ b/build/lib/monaco-api.js
@@ -27,7 +27,7 @@ function isDeclaration(ts, a) {
 }
 function visitTopLevelDeclarations(ts, sourceFile, visitor) {
     let stop = false;
-    let visit = (node) => {
+    const visit = (node) => {
         if (stop) {
             return;
         }
@@ -49,19 +49,19 @@ function visitTopLevelDeclarations(ts, sourceFile, visitor) {
     visit(sourceFile);
 }
 function getAllTopLevelDeclarations(ts, sourceFile) {
-    let all = [];
+    const all = [];
     visitTopLevelDeclarations(ts, sourceFile, (node) => {
         if (node.kind === ts.SyntaxKind.InterfaceDeclaration || node.kind === ts.SyntaxKind.ClassDeclaration || node.kind === ts.SyntaxKind.ModuleDeclaration) {
-            let interfaceDeclaration = node;
-            let triviaStart = interfaceDeclaration.pos;
-            let triviaEnd = interfaceDeclaration.name.pos;
-            let triviaText = getNodeText(sourceFile, { pos: triviaStart, end: triviaEnd });
+            const interfaceDeclaration = node;
+            const triviaStart = interfaceDeclaration.pos;
+            const triviaEnd = interfaceDeclaration.name.pos;
+            const triviaText = getNodeText(sourceFile, { pos: triviaStart, end: triviaEnd });
             if (triviaText.indexOf('@internal') === -1) {
                 all.push(node);
             }
         }
         else {
-            let nodeText = getNodeText(sourceFile, node);
+            const nodeText = getNodeText(sourceFile, node);
             if (nodeText.indexOf('@internal') === -1) {
                 all.push(node);
             }
@@ -95,7 +95,7 @@ function getNodeText(sourceFile, node) {
 function hasModifier(modifiers, kind) {
     if (modifiers) {
         for (let i = 0; i < modifiers.length; i++) {
-            let mod = modifiers[i];
+            const mod = modifiers[i];
             if (mod.kind === kind) {
                 return true;
             }
@@ -113,14 +113,14 @@ function isDefaultExport(ts, declaration) {
 function getMassagedTopLevelDeclarationText(ts, sourceFile, declaration, importName, usage, enums) {
     let result = getNodeText(sourceFile, declaration);
     if (declaration.kind === ts.SyntaxKind.InterfaceDeclaration || declaration.kind === ts.SyntaxKind.ClassDeclaration) {
-        let interfaceDeclaration = declaration;
+        const interfaceDeclaration = declaration;
         const staticTypeName = (isDefaultExport(ts, interfaceDeclaration)
             ? `${importName}.default`
             : `${importName}.${declaration.name.text}`);
         let instanceTypeName = staticTypeName;
         const typeParametersCnt = (interfaceDeclaration.typeParameters ? interfaceDeclaration.typeParameters.length : 0);
         if (typeParametersCnt > 0) {
-            let arr = [];
+            const arr = [];
             for (let i = 0; i < typeParametersCnt; i++) {
                 arr.push('any');
             }
@@ -129,7 +129,7 @@ function getMassagedTopLevelDeclarationText(ts, sourceFile, declaration, importN
         const members = interfaceDeclaration.members;
         members.forEach((member) => {
             try {
-                let memberText = getNodeText(sourceFile, member);
+                const memberText = getNodeText(sourceFile, member);
                 if (memberText.indexOf('@internal') >= 0 || memberText.indexOf('private') >= 0) {
                     result = result.replace(memberText, '');
                 }
@@ -152,7 +152,7 @@ function getMassagedTopLevelDeclarationText(ts, sourceFile, declaration, importN
     result = result.replace(/export default /g, 'export ');
     result = result.replace(/export declare /g, 'export ');
     result = result.replace(/declare /g, '');
-    let lines = result.split(/\r\n|\r|\n/);
+    const lines = result.split(/\r\n|\r|\n/);
     for (let i = 0; i < lines.length; i++) {
         if (/\s*\*/.test(lines[i])) {
             // very likely a comment
@@ -177,9 +177,9 @@ function format(ts, text, endl) {
         return text;
     }
     // Parse the source text
-    let sourceFile = ts.createSourceFile('file.ts', text, ts.ScriptTarget.Latest, /*setParentPointers*/ true);
+    const sourceFile = ts.createSourceFile('file.ts', text, ts.ScriptTarget.Latest, /*setParentPointers*/ true);
     // Get the formatting edits on the input sources
-    let edits = ts.formatting.formatDocument(sourceFile, getRuleProvider(tsfmt), tsfmt);
+    const edits = ts.formatting.formatDocument(sourceFile, getRuleProvider(tsfmt), tsfmt);
     // Apply the edits on the input code
     return applyEdits(text, edits);
     function countParensCurly(text) {
@@ -202,7 +202,7 @@ function format(ts, text, endl) {
         return r;
     }
     function preformat(text, endl) {
-        let lines = text.split(endl);
+        const lines = text.split(endl);
         let inComment = false;
         let inCommentDeltaIndent = 0;
         let indent = 0;
@@ -282,9 +282,9 @@ function format(ts, text, endl) {
         // Apply edits in reverse on the existing text
         let result = text;
         for (let i = edits.length - 1; i >= 0; i--) {
-            let change = edits[i];
-            let head = result.slice(0, change.span.start);
-            let tail = result.slice(change.span.start + change.span.length);
+            const change = edits[i];
+            const head = result.slice(0, change.span.start);
+            const tail = result.slice(change.span.start + change.span.length);
             result = head + change.newText + tail;
         }
         return result;
@@ -300,15 +300,15 @@ function createReplacerFromDirectives(directives) {
 }
 function createReplacer(data) {
     data = data || '';
-    let rawDirectives = data.split(';');
-    let directives = [];
+    const rawDirectives = data.split(';');
+    const directives = [];
     rawDirectives.forEach((rawDirective) => {
         if (rawDirective.length === 0) {
             return;
         }
-        let pieces = rawDirective.split('=>');
+        const pieces = rawDirective.split('=>');
         let findStr = pieces[0];
-        let replaceStr = pieces[1];
+        const replaceStr = pieces[1];
         findStr = findStr.replace(/[\-\\\{\}\*\+\?\|\^\$\.\,\[\]\(\)\#\s]/g, '\\$&');
         findStr = '\\b' + findStr + '\\b';
         directives.push([new RegExp(findStr, 'g'), replaceStr]);
@@ -317,32 +317,32 @@ function createReplacer(data) {
 }
 function generateDeclarationFile(ts, recipe, sourceFileGetter) {
     const endl = /\r\n/.test(recipe) ? '\r\n' : '\n';
-    let lines = recipe.split(endl);
-    let result = [];
+    const lines = recipe.split(endl);
+    const result = [];
     let usageCounter = 0;
-    let usageImports = [];
-    let usage = [];
+    const usageImports = [];
+    const usage = [];
     let failed = false;
     usage.push(`var a: any;`);
     usage.push(`var b: any;`);
     const generateUsageImport = (moduleId) => {
-        let importName = 'm' + (++usageCounter);
+        const importName = 'm' + (++usageCounter);
         usageImports.push(`import * as ${importName} from './${moduleId.replace(/\.d\.ts$/, '')}';`);
         return importName;
     };
-    let enums = [];
+    const enums = [];
     let version = null;
     lines.forEach(line => {
         if (failed) {
             return;
         }
-        let m0 = line.match(/^\/\/dtsv=(\d+)$/);
+        const m0 = line.match(/^\/\/dtsv=(\d+)$/);
         if (m0) {
             version = m0[1];
         }
-        let m1 = line.match(/^\s*#include\(([^;)]*)(;[^)]*)?\)\:(.*)$/);
+        const m1 = line.match(/^\s*#include\(([^;)]*)(;[^)]*)?\)\:(.*)$/);
         if (m1) {
-            let moduleId = m1[1];
+            const moduleId = m1[1];
             const sourceFile = sourceFileGetter(moduleId);
             if (!sourceFile) {
                 logErr(`While handling ${line}`);
@@ -351,14 +351,14 @@ function generateDeclarationFile(ts, recipe, sourceFileGetter) {
                 return;
             }
             const importName = generateUsageImport(moduleId);
-            let replacer = createReplacer(m1[2]);
-            let typeNames = m1[3].split(/,/);
+            const replacer = createReplacer(m1[2]);
+            const typeNames = m1[3].split(/,/);
             typeNames.forEach((typeName) => {
                 typeName = typeName.trim();
                 if (typeName.length === 0) {
                     return;
                 }
-                let declaration = getTopLevelDeclaration(ts, sourceFile, typeName);
+                const declaration = getTopLevelDeclaration(ts, sourceFile, typeName);
                 if (!declaration) {
                     logErr(`While handling ${line}`);
                     logErr(`Cannot find ${typeName}`);
@@ -369,9 +369,9 @@ function generateDeclarationFile(ts, recipe, sourceFileGetter) {
             });
             return;
         }
-        let m2 = line.match(/^\s*#includeAll\(([^;)]*)(;[^)]*)?\)\:(.*)$/);
+        const m2 = line.match(/^\s*#includeAll\(([^;)]*)(;[^)]*)?\)\:(.*)$/);
         if (m2) {
-            let moduleId = m2[1];
+            const moduleId = m2[1];
             const sourceFile = sourceFileGetter(moduleId);
             if (!sourceFile) {
                 logErr(`While handling ${line}`);
@@ -380,10 +380,10 @@ function generateDeclarationFile(ts, recipe, sourceFileGetter) {
                 return;
             }
             const importName = generateUsageImport(moduleId);
-            let replacer = createReplacer(m2[2]);
-            let typeNames = m2[3].split(/,/);
-            let typesToExcludeMap = {};
-            let typesToExcludeArr = [];
+            const replacer = createReplacer(m2[2]);
+            const typeNames = m2[3].split(/,/);
+            const typesToExcludeMap = {};
+            const typesToExcludeArr = [];
             typeNames.forEach((typeName) => {
                 typeName = typeName.trim();
                 if (typeName.length === 0) {
@@ -400,7 +400,7 @@ function generateDeclarationFile(ts, recipe, sourceFileGetter) {
                 }
                 else {
                     // node is ts.VariableStatement
-                    let nodeText = getNodeText(sourceFile, declaration);
+                    const nodeText = getNodeText(sourceFile, declaration);
                     for (let i = 0; i < typesToExcludeArr.length; i++) {
                         if (nodeText.indexOf(typesToExcludeArr[i]) >= 0) {
                             return;
@@ -605,7 +605,7 @@ class TypeScriptLanguageServiceHost {
     }
 }
 function execute() {
-    let r = run3(new DeclarationResolver(new FSProvider()));
+    const r = run3(new DeclarationResolver(new FSProvider()));
     if (!r) {
         throw new Error(`monaco.d.ts generation error - Cannot continue`);
     }
diff --git a/build/lib/standalone.js b/build/lib/standalone.js
index f2116eb159e..192a436899f 100644
--- a/build/lib/standalone.js
+++ b/build/lib/standalone.js
@@ -10,7 +10,7 @@ const path = require("path");
 const tss = require("./treeshaking");
 const REPO_ROOT = path.join(__dirname, '../../');
 const SRC_DIR = path.join(REPO_ROOT, 'src');
-let dirCache = {};
+const dirCache = {};
 function writeFile(filePath, contents) {
     function ensureDirs(dirPath) {
         if (dirCache[dirPath]) {
@@ -53,13 +53,13 @@ function extractEditor(options) {
             options.typings.push(`../node_modules/@types/${type}/index.d.ts`);
         });
     }
-    let result = tss.shake(options);
-    for (let fileName in result) {
+    const result = tss.shake(options);
+    for (const fileName in result) {
         if (result.hasOwnProperty(fileName)) {
             writeFile(path.join(options.destRoot, fileName), result[fileName]);
         }
     }
-    let copied = {};
+    const copied = {};
     const copyFile = (fileName) => {
         if (copied[fileName]) {
             return;
@@ -72,7 +72,7 @@ function extractEditor(options) {
     const writeOutputFile = (fileName, contents) => {
         writeFile(path.join(options.destRoot, fileName), contents);
     };
-    for (let fileName in result) {
+    for (const fileName in result) {
         if (result.hasOwnProperty(fileName)) {
             const fileContents = result[fileName];
             const info = ts.preProcessFile(fileContents);
@@ -119,7 +119,7 @@ function createESMSourcesAndResources2(options) {
     const OUT_FOLDER = path.join(REPO_ROOT, options.outFolder);
     const OUT_RESOURCES_FOLDER = path.join(REPO_ROOT, options.outResourcesFolder);
     const getDestAbsoluteFilePath = (file) => {
-        let dest = options.renames[file.replace(/\\/g, '/')] || file;
+        const dest = options.renames[file.replace(/\\/g, '/')] || file;
         if (dest === 'tsconfig.json') {
             return path.join(OUT_FOLDER, `tsconfig.json`);
         }
@@ -193,7 +193,7 @@ function createESMSourcesAndResources2(options) {
         if (dir.charAt(dir.length - 1) !== '/' || dir.charAt(dir.length - 1) !== '\\') {
             dir += '/';
         }
-        let result = [];
+        const result = [];
         _walkDirRecursive(dir, result, dir.length);
         return result;
     }
@@ -215,7 +215,7 @@ function createESMSourcesAndResources2(options) {
         }
         writeFile(absoluteFilePath, contents);
         function toggleComments(fileContents) {
-            let lines = fileContents.split(/\r\n|\r|\n/);
+            const lines = fileContents.split(/\r\n|\r|\n/);
             let mode = 0;
             for (let i = 0; i < lines.length; i++) {
                 const line = lines[i];
@@ -278,14 +278,14 @@ function transportCSS(module, enqueue, write) {
             let DATA = ';base64,' + fileContents.toString('base64');
             if (!forceBase64 && /\.svg$/.test(url)) {
                 // .svg => url encode as explained at https://codepen.io/tigt/post/optimizing-svgs-in-data-uris
-                let newText = fileContents.toString()
+                const newText = fileContents.toString()
                     .replace(/"/g, '\'')
                     .replace(/</g, '%3C')
                     .replace(/>/g, '%3E')
                     .replace(/&/g, '%26')
                     .replace(/#/g, '%23')
                     .replace(/\s+/g, ' ');
-                let encodedData = ',' + newText;
+                const encodedData = ',' + newText;
                 if (encodedData.length < DATA.length) {
                     DATA = encodedData;
                 }
diff --git a/build/lib/treeshaking.js b/build/lib/treeshaking.js
index 008eb27aca2..32881066917 100644
--- a/build/lib/treeshaking.js
+++ b/build/lib/treeshaking.js
@@ -32,7 +32,7 @@ function printDiagnostics(options, diagnostics) {
             result += `${path.join(options.sourcesRoot, diag.file.fileName)}`;
         }
         if (diag.file && diag.start) {
-            let location = diag.file.getLineAndCharacterOfPosition(diag.start);
+            const location = diag.file.getLineAndCharacterOfPosition(diag.start);
             result += `:${location.line + 1}:${location.character}`;
         }
         result += ` - ` + JSON.stringify(diag.messageText);
@@ -150,7 +150,7 @@ function processLibFiles(ts, options) {
             result[key] = sourceText;
             // precess dependencies and "recurse"
             const info = ts.preProcessFile(sourceText);
-            for (let ref of info.libReferenceDirectives) {
+            for (const ref of info.libReferenceDirectives) {
                 stack.push(ref.fileName);
             }
         }
@@ -503,7 +503,7 @@ function markNodes(ts, languageService, options) {
                         }
                         // queue the heritage clauses
                         if (declaration.heritageClauses) {
-                            for (let heritageClause of declaration.heritageClauses) {
+                            for (const heritageClause of declaration.heritageClauses) {
                                 enqueue_black(heritageClause);
                             }
                         }
@@ -551,7 +551,7 @@ function generateResult(ts, languageService, shakeLevel) {
     if (!program) {
         throw new Error('Could not get program from language service');
     }
-    let result = {};
+    const result = {};
     const writeFile = (filePath, contents) => {
         result[filePath] = contents;
     };
@@ -567,7 +567,7 @@ function generateResult(ts, languageService, shakeLevel) {
             }
             return;
         }
-        let text = sourceFile.text;
+        const text = sourceFile.text;
         let result = '';
         function keep(node) {
             result += text.substring(node.pos, node.end);
@@ -597,7 +597,7 @@ function generateResult(ts, languageService, shakeLevel) {
                         }
                     }
                     else {
-                        let survivingImports = [];
+                        const survivingImports = [];
                         for (const importNode of node.importClause.namedBindings.elements) {
                             if (getColor(importNode) === 2 /* NodeColor.Black */) {
                                 survivingImports.push(importNode.getFullText(sourceFile));
@@ -626,7 +626,7 @@ function generateResult(ts, languageService, shakeLevel) {
             }
             if (ts.isExportDeclaration(node)) {
                 if (node.exportClause && node.moduleSpecifier && ts.isNamedExports(node.exportClause)) {
-                    let survivingExports = [];
+                    const survivingExports = [];
                     for (const exportSpecifier of node.exportClause.elements) {
                         if (getColor(exportSpecifier) === 2 /* NodeColor.Black */) {
                             survivingExports.push(exportSpecifier.getFullText(sourceFile));
@@ -647,8 +647,8 @@ function generateResult(ts, languageService, shakeLevel) {
                         // keep method
                         continue;
                     }
-                    let pos = member.pos - node.pos;
-                    let end = member.end - node.pos;
+                    const pos = member.pos - node.pos;
+                    const end = member.end - node.pos;
                     toWrite = toWrite.substring(0, pos) + toWrite.substring(end);
                 }
                 return write(toWrite);
diff --git a/build/lib/tsb/builder.js b/build/lib/tsb/builder.js
index cb700a54077..db9609a49f3 100644
--- a/build/lib/tsb/builder.js
+++ b/build/lib/tsb/builder.js
@@ -28,7 +28,14 @@ function createTypeScriptBuilder(config, projectFile, cmd) {
             log(colors.cyan(topic), message);
         }
     }
-    let host = new LanguageServiceHost(cmd, projectFile, _log), service = ts.createLanguageService(host, ts.createDocumentRegistry()), lastBuildVersion = Object.create(null), lastDtsHash = Object.create(null), userWantsDeclarations = cmd.options.declaration, oldErrors = Object.create(null), headUsed = process.memoryUsage().heapUsed, emitSourceMapsInStream = true;
+    const host = new LanguageServiceHost(cmd, projectFile, _log);
+    const service = ts.createLanguageService(host, ts.createDocumentRegistry());
+    const lastBuildVersion = Object.create(null);
+    const lastDtsHash = Object.create(null);
+    const userWantsDeclarations = cmd.options.declaration;
+    let oldErrors = Object.create(null);
+    let headUsed = process.memoryUsage().heapUsed;
+    let emitSourceMapsInStream = true;
     // always emit declaraction files
     host.getCompilationSettings().declaration = true;
     function file(file) {
@@ -85,8 +92,8 @@ function createTypeScriptBuilder(config, projectFile, cmd) {
                 process.nextTick(function () {
                     if (/\.d\.ts$/.test(fileName)) {
                         // if it's already a d.ts file just emit it signature
-                        let snapshot = host.getScriptSnapshot(fileName);
-                        let signature = crypto.createHash('md5')
+                        const snapshot = host.getScriptSnapshot(fileName);
+                        const signature = crypto.createHash('md5')
                             .update(snapshot.getText(0, snapshot.getLength()))
                             .digest('base64');
                         return resolve({
@@ -95,10 +102,10 @@ function createTypeScriptBuilder(config, projectFile, cmd) {
                             files: []
                         });
                     }
-                    let output = service.getEmitOutput(fileName);
-                    let files = [];
+                    const output = service.getEmitOutput(fileName);
+                    const files = [];
                     let signature;
-                    for (let file of output.outputFiles) {
+                    for (const file of output.outputFiles) {
                         if (!emitSourceMapsInStream && /\.js\.map$/.test(file.name)) {
                             continue;
                         }
@@ -111,19 +118,19 @@ function createTypeScriptBuilder(config, projectFile, cmd) {
                                 continue;
                             }
                         }
-                        let vinyl = new Vinyl({
+                        const vinyl = new Vinyl({
                             path: file.name,
                             contents: Buffer.from(file.text),
                             base: !config._emitWithoutBasePath && baseFor(host.getScriptSnapshot(fileName)) || undefined
                         });
                         if (!emitSourceMapsInStream && /\.js$/.test(file.name)) {
-                            let sourcemapFile = output.outputFiles.filter(f => /\.js\.map$/.test(f.name))[0];
+                            const sourcemapFile = output.outputFiles.filter(f => /\.js\.map$/.test(f.name))[0];
                             if (sourcemapFile) {
-                                let extname = path.extname(vinyl.relative);
-                                let basename = path.basename(vinyl.relative, extname);
-                                let dirname = path.dirname(vinyl.relative);
-                                let tsname = (dirname === '.' ? '' : dirname + '/') + basename + '.ts';
-                                let sourceMap = JSON.parse(sourcemapFile.text);
+                                const extname = path.extname(vinyl.relative);
+                                const basename = path.basename(vinyl.relative, extname);
+                                const dirname = path.dirname(vinyl.relative);
+                                const tsname = (dirname === '.' ? '' : dirname + '/') + basename + '.ts';
+                                const sourceMap = JSON.parse(sourcemapFile.text);
                                 sourceMap.sources[0] = tsname.replace(/\\/g, '/');
                                 vinyl.sourceMap = sourceMap;
                             }
@@ -138,15 +145,15 @@ function createTypeScriptBuilder(config, projectFile, cmd) {
                 });
             });
         }
-        let newErrors = Object.create(null);
-        let t1 = Date.now();
-        let toBeEmitted = [];
-        let toBeCheckedSyntactically = [];
-        let toBeCheckedSemantically = [];
-        let filesWithChangedSignature = [];
-        let dependentFiles = [];
-        let newLastBuildVersion = new Map();
-        for (let fileName of host.getScriptFileNames()) {
+        const newErrors = Object.create(null);
+        const t1 = Date.now();
+        const toBeEmitted = [];
+        const toBeCheckedSyntactically = [];
+        const toBeCheckedSemantically = [];
+        const filesWithChangedSignature = [];
+        const dependentFiles = [];
+        const newLastBuildVersion = new Map();
+        for (const fileName of host.getScriptFileNames()) {
             if (lastBuildVersion[fileName] !== host.getScriptVersion(fileName)) {
                 toBeEmitted.push(fileName);
                 toBeCheckedSyntactically.push(fileName);
@@ -154,8 +161,8 @@ function createTypeScriptBuilder(config, projectFile, cmd) {
             }
         }
         return new Promise(resolve => {
-            let semanticCheckInfo = new Map();
-            let seenAsDependentFile = new Set();
+            const semanticCheckInfo = new Map();
+            const seenAsDependentFile = new Set();
             function workOnNext() {
                 let promise;
                 // let fileName: string;
@@ -168,9 +175,9 @@ function createTypeScriptBuilder(config, projectFile, cmd) {
                 }
                 // (1st) emit code
                 else if (toBeEmitted.length) {
-                    let fileName = toBeEmitted.pop();
+                    const fileName = toBeEmitted.pop();
                     promise = emitSoon(fileName).then(value => {
-                        for (let file of value.files) {
+                        for (const file of value.files) {
                             _log('[emit code]', file.path);
                             out(file);
                         }
@@ -189,7 +196,7 @@ function createTypeScriptBuilder(config, projectFile, cmd) {
                 }
                 // (2nd) check syntax
                 else if (toBeCheckedSyntactically.length) {
-                    let fileName = toBeCheckedSyntactically.pop();
+                    const fileName = toBeCheckedSyntactically.pop();
                     _log('[check syntax]', fileName);
                     promise = checkSyntaxSoon(fileName).then(diagnostics => {
                         delete oldErrors[fileName];
@@ -224,7 +231,7 @@ function createTypeScriptBuilder(config, projectFile, cmd) {
                 // (4th) check dependents
                 else if (filesWithChangedSignature.length) {
                     while (filesWithChangedSignature.length) {
-                        let fileName = filesWithChangedSignature.pop();
+                        const fileName = filesWithChangedSignature.pop();
                         if (!isExternalModule(service.getProgram().getSourceFile(fileName))) {
                             _log('[check semantics*]', fileName + ' is an internal module and it has changed shape -> check whatever hasn\'t been checked yet');
                             toBeCheckedSemantically.push(...host.getScriptFileNames());
@@ -243,7 +250,7 @@ function createTypeScriptBuilder(config, projectFile, cmd) {
                     }
                     if (fileName) {
                         seenAsDependentFile.add(fileName);
-                        let value = semanticCheckInfo.get(fileName);
+                        const value = semanticCheckInfo.get(fileName);
                         if (value === 0) {
                             // already validated successfully -> look at dependents next
                             host.collectDependents(fileName, dependentFiles);
@@ -400,7 +407,7 @@ class LanguageServiceHost {
         }
         if (!old || old.getVersion() !== snapshot.getVersion()) {
             this._dependenciesRecomputeList.push(filename);
-            let node = this._dependencies.lookup(filename);
+            const node = this._dependencies.lookup(filename);
             if (node) {
                 node.outgoing = Object.create(null);
             }
@@ -479,7 +486,7 @@ class LanguageServiceHost {
                 }
             }
             if (!found) {
-                for (let key in this._fileNameToDeclaredModule) {
+                for (const key in this._fileNameToDeclaredModule) {
                     if (this._fileNameToDeclaredModule[key] && ~this._fileNameToDeclaredModule[key].indexOf(ref.fileName)) {
                         this._dependencies.inertEdge(filename, key);
                     }
diff --git a/build/lib/tsb/index.js b/build/lib/tsb/index.js
index bd30013092c..8a7e64e4eb7 100644
--- a/build/lib/tsb/index.js
+++ b/build/lib/tsb/index.js
@@ -60,7 +60,7 @@ function create(projectPath, existingOptions, verbose = false, onError = _defaul
     const result = (token) => createStream(token);
     result.src = (opts) => {
         let _pos = 0;
-        let _fileNames = cmdLine.fileNames.slice(0);
+        const _fileNames = cmdLine.fileNames.slice(0);
         return new class extends stream_1.Readable {
             constructor() {
                 super({ objectMode: true });
diff --git a/build/lib/tsb/utils.js b/build/lib/tsb/utils.js
index 810297dc246..cc8605758ce 100644
--- a/build/lib/tsb/utils.js
+++ b/build/lib/tsb/utils.js
@@ -30,7 +30,7 @@ var collections;
     }
     collections.lookupOrInsert = lookupOrInsert;
     function forEach(collection, callback) {
-        for (let key in collection) {
+        for (const key in collection) {
             if (hasOwnProperty.call(collection, key)) {
                 callback({
                     key: key,
diff --git a/build/lib/util.js b/build/lib/util.js
index 4efe2b3a046..0f6cf5875fc 100644
--- a/build/lib/util.js
+++ b/build/lib/util.js
@@ -240,7 +240,7 @@ function _rreaddir(dirPath, prepend, result) {
     }
 }
 function rreddir(dirPath) {
-    let result = [];
+    const result = [];
     _rreaddir(dirPath, '', result);
     return result;
 }
@@ -344,7 +344,7 @@ function createExternalLoaderConfig(webEndpoint, commit, quality) {
         return undefined;
     }
     webEndpoint = webEndpoint + `/${quality}/${commit}`;
-    let nodePaths = acquireWebNodePaths();
+    const nodePaths = acquireWebNodePaths();
     Object.keys(nodePaths).map(function (key, _) {
         nodePaths[key] = `${webEndpoint}/node_modules/${key}/${nodePaths[key]}`;
     });