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

module-

types-

class-

func-

control-

error-

naming-

literal-

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