Google TypeScript Best Practices

Comprehensive TypeScript style guide based on Google's internal standards, designed for AI agents and LLMs. Contains 45 rules across 8 categories, prioritized by impact to guide automated refactoring and code generation.

When to Apply

Reference these guidelines when:

• •Writing new TypeScript code
• •Organizing modules and imports
• •Designing type annotations and interfaces
• •Creating classes and functions
• •Reviewing code for style consistency
• •Refactoring existing TypeScript code

Rule Categories by Priority

Quick Reference

1. Module Organization (CRITICAL)

• •module-named-exports - Use named exports over default exports
• •module-no-mutable-exports - Avoid mutable exports
• •module-es6-modules - Use ES6 modules exclusively
• •module-no-namespaces - Avoid TypeScript namespaces
• •module-import-paths - Use relative paths for project imports
• •module-import-type - Use import type for type-only imports
• •module-export-api-surface - Minimize exported API surface

2. Type Safety (CRITICAL)

• •types-no-any - Never use the any type
• •types-prefer-interfaces - Prefer interfaces over type aliases for objects
• •types-explicit-structural - Explicitly annotate structural types
• •types-nullable-patterns - Handle nullable types correctly
• •types-array-syntax - Use consistent array type syntax
• •types-no-wrapper-types - Never use wrapper object types
• •types-prefer-map-set - Prefer Map and Set over index signatures
• •types-no-empty-object - Avoid empty object type

3. Class Design (HIGH)

• •class-parameter-properties - Use parameter properties for constructor assignment
• •class-readonly-properties - Mark properties readonly when never reassigned
• •class-no-private-fields - Use TypeScript private over private fields
• •class-no-static-containers - Avoid container classes with only static members
• •class-constructor-parens - Always use parentheses in constructor calls
• •class-no-prototype-manipulation - Never manipulate prototypes directly

4. Function Patterns (HIGH)

• •func-declarations-over-expressions - Prefer function declarations over expressions
• •func-arrow-concise-bodies - Use concise arrow function bodies appropriately
• •func-avoid-this-rebinding - Avoid rebinding this
• •func-rest-parameters - Use rest parameters over arguments
• •func-generator-syntax - Use correct generator function syntax
• •func-default-parameters - Use default parameters sparingly

5. Control Flow (MEDIUM-HIGH)

• •control-always-use-braces - Always use braces for control structures
• •control-triple-equals - Always use triple equals
• •control-for-of-iteration - Prefer for-of over for-in for arrays
• •control-switch-default - Always include default case in switch
• •control-no-assignment-in-condition - Avoid assignment in conditional expressions

6. Error Handling (MEDIUM)

• •error-throw-errors - Always throw Error instances
• •error-catch-unknown - Type catch clause variables as unknown
• •error-empty-catch-comments - Document empty catch blocks
• •error-avoid-assertions - Avoid type and non-null assertions

7. Naming & Style (MEDIUM)

• •naming-identifier-styles - Use correct identifier naming styles
• •naming-descriptive-names - Use descriptive names
• •naming-no-decorative-underscores - Avoid decorative underscores
• •naming-no-interface-prefix - No I prefix for interfaces
• •naming-constants - Use CONSTANT_CASE for true constants

8. Literals & Coercion (LOW-MEDIUM)

• •literal-single-quotes - Use single quotes for strings
• •literal-number-formats - Use correct number literal formats
• •literal-explicit-coercion - Use explicit type coercion
• •literal-array-constructor - Avoid Array constructor

How to Use

Read individual reference files for detailed explanations and code examples:

• •Section definitions - Category structure and impact levels
• •Rule template - Template for adding new rules

Reference Files