PredicateWithIndex - API reference

API reference › @evolu/common › Types › PredicateWithIndex

type PredicateWithIndex<T> = (value: T, index: number) => boolean;

Defined in: packages/common/src/Types.ts:99

Checks a condition on a value at a given index and returns a boolean.

Useful for callbacks that need both the element and its position.

Filtering by position

import type { PredicateWithIndex } from "@evolu/common";

const isEvenIndex: PredicateWithIndex<string> = (value, index) =>
  index % 2 === 0;

expect(["a", "b", "c", "d"].filter(isEvenIndex)).toEqual(["a", "c"]);