Enable preferConst in TS project

.eslintignore

@@ -14,3 +14,4 @@
 **/extensions/**/build/**
 **/extensions/markdown-language-features/media/**
 **/extensions/typescript-basics/test/colorize-fixtures/**
+**/extensions/typescript-language-features/dist/**

extensions/typescript-language-features/.eslintrc.json

@@ -0,0 +1,5 @@
+{
+	"rules": {
+		"prefer-const": "error"
+	}
+}

extensions/typescript-language-features/src/languageFeatures/completions.ts

@@ -533,7 +533,7 @@ class TypeScriptCompletionItemProvider implements vscode.CompletionItemProvider<
 
 		let includesPackageJsonImport = false;
 		const items: MyCompletionItem[] = [];
-		for (let entry of entries) {
+		for (const entry of entries) {
 			if (!shouldExcludeCompletionEntry(entry, completionConfiguration)) {
 				items.push(new MyCompletionItem(position, document, entry, completionContext, metadata));
 				includesPackageJsonImport = !!entry.isPackageJsonImport;

extensions/typescript-language-features/src/languageFeatures/semanticTokens.ts

@@ -73,7 +73,7 @@ class DocumentSemanticTokensProvider implements vscode.DocumentSemanticTokensPro
 			return null;
 		}
 
-		let versionBeforeRequest = document.version;
+		const versionBeforeRequest = document.version;
 
 		const response = await (this.client as ExperimentalProtocol.IExtendedTypeScriptServiceClient).execute('encodedSemanticClassifications-full', requestArg, token, {
 			cancelOnResourceChange: document.uri
@@ -137,7 +137,7 @@ class DocumentSemanticTokensProvider implements vscode.DocumentSemanticTokensPro
 function waitForDocumentChangesToEnd(document: vscode.TextDocument) {
 	let version = document.version;
 	return new Promise<void>((s) => {
-		let iv = setInterval(_ => {
+		const iv = setInterval(_ => {
 			if (document.version === version) {
 				clearInterval(iv);
 				s();

extensions/typescript-language-features/src/tsServer/serverProcess.electron.ts

@@ -39,7 +39,7 @@ class ProtocolBuffer {
 		if (this.buffer.length - this.index >= toAppend.length) {
 			toAppend.copy(this.buffer, this.index, 0, toAppend.length);
 		} else {
-			let newSize = (Math.ceil((this.index + toAppend.length) / defaultSize) + 1) * defaultSize;
+			const newSize = (Math.ceil((this.index + toAppend.length) / defaultSize) + 1) * defaultSize;
 			if (this.index === 0) {
 				this.buffer = Buffer.allocUnsafe(newSize);
 				toAppend.copy(this.buffer, 0, 0, toAppend.length);
@@ -61,14 +61,14 @@ class ProtocolBuffer {
 			return result;
 		}
 		current += contentLengthSize;
-		let start = current;
+		const start = current;
 		while (current < this.index && this.buffer[current] !== backslashR) {
 			current++;
 		}
 		if (current + 3 >= this.index || this.buffer[current + 1] !== backslashN || this.buffer[current + 2] !== backslashR || this.buffer[current + 3] !== backslashN) {
 			return result;
 		}
-		let data = this.buffer.toString('utf8', start, current);
+		const data = this.buffer.toString('utf8', start, current);
 		result = parseInt(data);
 		this.buffer = this.buffer.slice(current + 4);
 		this.index = this.index - (current + 4);
@@ -79,7 +79,7 @@ class ProtocolBuffer {
 		if (this.index < length) {
 			return null;
 		}
-		let result = this.buffer.toString('utf8', 0, length);
+		const result = this.buffer.toString('utf8', 0, length);
 		let sourceStart = length;
 		while (sourceStart < this.index && (this.buffer[sourceStart] === backslashR || this.buffer[sourceStart] === backslashN)) {
 			sourceStart++;

extensions/typescript-language-features/src/typescriptServiceClient.ts

@@ -374,7 +374,7 @@ export default class TypeScriptServiceClient extends Disposable implements IType
 		this.info(`Using tsserver from: ${version.path}`);
 
 		const apiVersion = version.apiVersion || API.defaultVersion;
-		let mytoken = ++this.token;
+		const mytoken = ++this.token;
 		const handle = this.typescriptServerSpawner.spawn(version, this.capabilities, this.configuration, this.pluginManager, this.cancellerFactory, {
 			onFatalError: (command, err) => this.fatalError(command, err),
 		});