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