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TypeScript Styleguide

Indexed Objects: Record<K, V> vs Index Signatures

Two ways to define indexed object types in TypeScript. Explore the differences between Record<K, V> utility type and index signature syntax.

82%

Use Record Utility Type

18%

Use Index Signature

Record Utility Type

Using the Record<K, V> utility type to define indexed object properties.

Code Example

example.ts (Record<K, V>)
type UserRoles = Record<'admin' | 'user' | 'guest', Role>;
type ConfigMap = Record<string, string | number>;

interface Config {
  settings: Record<string, unknown>;
  features: Record<FeatureName, boolean>;
}

Key Benefits

  • Concise and readable utility type
  • Clear what keys and values are
  • Works well with union key types
  • Easy to understand intent
  • Modern TypeScript approach
  • Better for complex key types

Statistics

Index Signature

Using index signatures to define dynamically keyed object properties.

Code Example

example.ts (index signature)
interface UserRoles {
  [role: string]: Role;
}

type ConfigMap = {
  [key: string]: string | number;
};

interface Config {
  settings: { [key: string]: unknown };
  features: { [key: FeatureName]: boolean };
}

Key Benefits

  • Classic TypeScript syntax
  • Explicitly shows dynamic keys
  • More flexible in some contexts
  • Works in interfaces and types
  • Better for object-like structures
  • Clearer when extending properties

Statistics

Additional Insights

More data points to help you make an informed decision for your team.

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