Function indexBy

Emits indexed values that pass the predicate test.

import {pipe, indexBy} from 'iter-ops';

const i = pipe(
    [12, 7, 30, 9],
    indexBy(a => a % 2 === 0) // index even numbers
);

console.log(...i); //=> {index: 0, value: 12}, {index: 2, value: 30}
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Note that the predicate can only return a Promise inside an asynchronous pipeline, or else the Promise will be treated as a truthy value.

See

• IIndexedValue