[API reference](https://evolu.dev/docs/api-reference) › [@evolu/common](https://evolu.dev/docs/api-reference/common) › [Schedule](https://evolu.dev/docs/api-reference/common/Schedule) › collectWhileScheduleOutput

```ts
function collectWhileScheduleOutput<Output>(
  predicate: Predicate<Output>,
): <Input>(
  schedule: Schedule<Output, Input>,
) => Schedule<readonly Output[], Input>;
```

Defined in: [packages/common/src/Schedule.ts:1722](https://github.com/evoluhq/evolu/blob/037c390af081e9944d616ff298a729515c5c5ab7/packages/common/src/Schedule.ts#L1722)

Collects outputs while a predicate is true.

More flexible than [collectAllScheduleOutputs](https://evolu.dev/docs/api-reference/common/Schedule/functions/collectAllScheduleOutputs) — stops collecting when
the predicate returns false.

### Collecting while output matches

```ts
import {
  assertErr,
  assertOk,
  collectWhileScheduleOutput,
  done,
  exponential,
  testCreateDeps,
  type Millis,
} from "@evolu/common";

// Collect delays only while they remain below one second.
const smallDelays = collectWhileScheduleOutput((delay: Millis) => delay < 1000)(
  exponential("100ms"),
);
const step = smallDelays(testCreateDeps());
step(undefined);
step(undefined);
step(undefined);
assertOk(step(undefined), [[100, 200, 400, 800], 800]);
assertErr(step(undefined), done());
```