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](references/module-named-exports.md) - Use named exports over default exports
• [module-no-mutable-exports](references/module-no-mutable-exports.md) - Avoid mutable exports
• [module-es6-modules](references/module-es6-modules.md) - Use ES6 modules exclusively
• [module-no-namespaces](references/module-no-namespaces.md) - Avoid TypeScript namespaces
• [module-import-paths](references/module-import-paths.md) - Use relative paths for project imports
• [module-import-type](references/module-import-type.md) - Use import type for type-only imports
• [module-export-api-surface](references/module-export-api-surface.md) - Minimize exported API surface

2. Type Safety (CRITICAL)

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

3. Class Design (HIGH)

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

4. Function Patterns (HIGH)

• [func-declarations-over-expressions](references/func-declarations-over-expressions.md) - Prefer function declarations over expressions
• [func-arrow-concise-bodies](references/func-arrow-concise-bodies.md) - Use concise arrow function bodies appropriately
• [func-avoid-this-rebinding](references/func-avoid-this-rebinding.md) - Avoid rebinding this
• [func-rest-parameters](references/func-rest-parameters.md) - Use rest parameters over arguments
• [func-generator-syntax](references/func-generator-syntax.md) - Use correct generator function syntax
• [func-default-parameters](references/func-default-parameters.md) - Use default parameters sparingly

5. Control Flow (MEDIUM-HIGH)

• [control-always-use-braces](references/control-always-use-braces.md) - Always use braces for control structures
• [control-triple-equals](references/control-triple-equals.md) - Always use triple equals
• [control-for-of-iteration](references/control-for-of-iteration.md) - Prefer for-of over for-in for arrays
• [control-switch-default](references/control-switch-default.md) - Always include default case in switch
• [control-no-assignment-in-condition](references/control-no-assignment-in-condition.md) - Avoid assignment in conditional expressions

6. Error Handling (MEDIUM)

• [error-throw-errors](references/error-throw-errors.md) - Always throw Error instances
• [error-catch-unknown](references/error-catch-unknown.md) - Type catch clause variables as unknown
• [error-empty-catch-comments](references/error-empty-catch-comments.md) - Document empty catch blocks
• [error-avoid-assertions](references/error-avoid-assertions.md) - Avoid type and non-null assertions

7. Naming & Style (MEDIUM)

• [naming-identifier-styles](references/naming-identifier-styles.md) - Use correct identifier naming styles
• [naming-descriptive-names](references/naming-descriptive-names.md) - Use descriptive names
• [naming-no-decorative-underscores](references/naming-no-decorative-underscores.md) - Avoid decorative underscores
• [naming-no-interface-prefix](references/naming-no-interface-prefix.md) - No I prefix for interfaces
• [naming-constants](references/naming-constants.md) - Use CONSTANT_CASE for true constants

8. Literals & Coercion (LOW-MEDIUM)

• [literal-single-quotes](references/literal-single-quotes.md) - Use single quotes for strings
• [literal-number-formats](references/literal-number-formats.md) - Use correct number literal formats
• [literal-explicit-coercion](references/literal-explicit-coercion.md) - Use explicit type coercion
• [literal-array-constructor](references/literal-array-constructor.md) - Avoid Array constructor

How to Use

Read individual reference files for detailed explanations and code examples:

• [Section definitions](references/_sections.md) - Category structure and impact levels
• [Rule template](assets/templates/_template.md) - Template for adding new rules

Reference Files