PredicateWithIndex - API reference

API reference › @evolu/common › Types › PredicateWithIndex

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

Defined in: packages/common/src/Types.ts:108

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 { assertEqual, type PredicateWithIndex } from "@evolu/common";

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

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