indexedObjectTypes

Reports indexed object types that don't match the configured style.

✅ This rule is included in the ts stylistic and stylisticStrict presets.

TypeScript provides two equivalent ways to define indexed object types: Record<K, V> and { [key: K]: V }. Using one style consistently improves code readability.

This rule enforces consistent usage of either Record<K, V> (default) or index signatures.

interface 
interface Data
Data {
  [
key: string
key: string]: number;
}

type 
type StringMap = {
    [key: string]: string;
}
StringMap = { [
key: string
key: string]: string };

function 
function process(data: {
    [key: string]: number;
}): void
process(
data: {
    [key: string]: number;
}
data: { [
key: string
key: string]: number }): void {}

type 
type Data = {
    [x: string]: number;
}
Data = 
type Record<K extends keyof any, T> = { [P in K]: T; }
Construct a type with a set of properties K of type T
Record<string, number>;

type 
type StringMap = {
    [x: string]: string;
}
StringMap = 
type Record<K extends keyof any, T> = { [P in K]: T; }
Construct a type with a set of properties K of type T
Record<string, string>;

function 
function process(data: Record<string, number>): void
process(
data: Record<string, number>
data: 
type Record<K extends keyof any, T> = { [P in K]: T; }
Construct a type with a set of properties K of type T
Record<string, number>): void {}

Options

`style`

"record" (default): Prefer Record<K, V> over index signatures.
"index-signature": Prefer index signatures over Record<K, V>.

When set to "index-signature":

❌ Incorrect
✅ Correct

type 
type Data = {
    [x: string]: number;
}
Data = 
type Record<K extends keyof any, T> = { [P in K]: T; }
Construct a type with a set of properties K of type T
Record<string, number>;

type 
type Data = {
    [key: string]: number;
}
Data = { [
key: string
key: string]: number };

When Not To Use It

If your project already has an established convention for indexed object types that you don’t want to enforce, or if you prefer allowing both styles for flexibility, you may disable this rule.

Equivalents in Other Linters

ESLint: @typescript-eslint/consistent-indexed-object-style
Oxlint: typescript/consistent-indexed-object-style

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