Add eslint rule to prevent bracket syntax for property access

.eslint-plugin-local/code-no-bracket-notation-for-identifiers.ts

@@ -0,0 +1,84 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+import * as eslint from 'eslint';
+import { TSESTree } from '@typescript-eslint/utils';
+
+/**
+ * Disallow bracket notation for accessing properties that are valid identifiers,
+ * especially private members (starting with underscore). Bracket notation should
+ * only be used for properties with special characters or computed property names.
+ *
+ * Bad:  obj['_privateMember']
+ * Bad:  obj['normalProperty']
+ * Good: obj._privateMember  // TypeScript will catch private access
+ * Good: obj.normalProperty
+ * Good: obj['property-with-dashes']
+ * Good: obj[computedKey]
+ */
+export = new class NoBracketNotationForIdentifiers implements eslint.Rule.RuleModule {
+
+	readonly meta: eslint.Rule.RuleMetaData = {
+		type: 'problem',
+		docs: {
+			description: 'Disallow bracket notation for accessing properties that are valid identifiers'
+		},
+		messages: {
+			noBracketNotation: 'Use dot notation instead of bracket notation for property \'{{property}}\'. Bracket notation bypasses TypeScript\'s type checking and access modifiers.'
+		},
+		schema: [],
+		fixable: 'code'
+	};
+
+	create(context: eslint.Rule.RuleContext): eslint.Rule.RuleListener {
+
+		/**
+		 * Check if a string is a valid JavaScript identifier
+		 */
+		function isValidIdentifier(str: string): boolean {
+			// Check if it's a valid JavaScript identifier
+			// Must start with letter, underscore, or dollar sign
+			// Can contain letters, digits, underscores, or dollar signs
+			return /^[a-zA-Z_$][a-zA-Z0-9_$]*$/.test(str);
+		}
+
+		return {
+			MemberExpression(node: any) {
+				const memberExpr = node as TSESTree.MemberExpression;
+
+				// Only check computed member expressions (bracket notation)
+				if (!memberExpr.computed) {
+					return;
+				}
+
+				// Only check string literals in brackets
+				if (memberExpr.property.type !== 'Literal' || typeof memberExpr.property.value !== 'string') {
+					return;
+				}
+
+				const propertyName = memberExpr.property.value;
+
+				// If it's a valid identifier, report it
+				if (isValidIdentifier(propertyName)) {
+					context.report({
+						node: memberExpr.property,
+						messageId: 'noBracketNotation',
+						data: {
+							property: propertyName
+						},
+						fix(fixer) {
+							// Convert obj['property'] to obj.property
+							// We need to replace the ['property'] part with .property
+							const sourceCode = context.getSourceCode();
+							const objectText = sourceCode.getText(memberExpr.object as unknown as eslint.Rule.Node);
+							const dotNotation = `${objectText}.${propertyName}`;
+							return fixer.replaceText(node, dotNotation);
+						}
+					});
+				}
+			}
+		};
+	}
+};

eslint.config.js

@@ -78,6 +78,7 @@ export default tseslint.config(
 			'semi': 'off',
 			'local/code-translation-remind': 'warn',
 			'local/code-no-native-private': 'warn',
+			'local/code-no-bracket-notation-for-identifiers': 'warn',
 			'local/code-parameter-properties-must-have-explicit-accessibility': 'warn',
 			'local/code-no-nls-in-standalone-editor': 'warn',
 			'local/code-no-potentially-unsafe-disposables': 'warn',