ts-r
  • Error
  • Reported by the type checker

TS2411

Property '{0}' of type '{1}' is not assignable to '{2}' index type '{3}'.

A property doesn't fit the type of an index signature in the same type. Change the property's type, or widen the index signature.

What it means

An index signature like [key: string]: number says every string-named property has that type, including the ones declared explicitly. A named property whose type isn't assignable to the index signature's type breaks that promise.

Example

index.ts
export interface Scores {
  [name: string]: number;
  label: string;
}
ts-r-check -p tsconfig.json --pretty false ts-r output
index.ts(3,3): error TS2411: Property 'label' of type 'string' is not assignable to 'string' index type 'number'.

Recorded by node scripts/verify-examples.mjs with ts-r built from commit 6deaf01. The example uses the default tsconfig: strict, target: es2022, module: esnext, moduleResolution: bundler.

How to fix

  • Widen the index signature: [name: string]: number | string.
  • Or move the odd property out: { label: string; scores: Record<string, number> }.