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consistent-indexed-object-style

Require or disallow the Record type.

🎨

Extending "plugin:@typescript-eslint/stylistic" in an ESLint configuration enables this rule.

🔧

Some problems reported by this rule are automatically fixable by the --fix ESLint command line option.

💡

Some problems reported by this rule are manually fixable by editor suggestions.

TypeScript supports defining arbitrary object keys using an index signature or mapped type. TypeScript also has a builtin type named Record to create an empty object defining only an index signature. For example, the following types are equal:

interface IndexSignatureInterface {
  [key: string]: unknown;
}

type IndexSignatureType = {
  [key: string]: unknown;
};

type MappedType = {
  [key in string]: unknown;
};

type RecordType = Record<string, unknown>;

Using one declaration form consistently improves code readability.

eslint.config.mjs
export default tseslint.config({
  rules: {
    "@typescript-eslint/consistent-indexed-object-style": "error"
  }
});

Try this rule in the playground ↗

Options​

This rule accepts the following options:

type Options = [
  /** Which indexed object syntax to prefer. */
  | 'index-signature'
  /** Which indexed object syntax to prefer. */
  | 'record',
];

const defaultOptions: Options = ['record'];
  • 'record' (default): only allow the Record type.
  • 'index-signature': only allow index signatures.

'record'​

interface IndexSignatureInterface {
  [key: string]: unknown;
}

type IndexSignatureType = {
  [key: string]: unknown;
};

type MappedType = {
  [key in string]: unknown;
};
Open in Playground

'index-signature'​

type RecordType = Record<string, unknown>;
Open in Playground

When Not To Use It​

This rule is purely a stylistic rule for maintaining consistency in your project. You can turn it off if you don't want to keep a consistent style for indexed object types.

However, keep in mind that inconsistent style can harm readability in a project. We recommend picking a single option for this rule that works best for your project.

Resources​