API · Async

`massThen()`

Call `.then()` on every promise value and emit the resulting promises.

Signature

massThen<U>(
  fn: (value: ResolvedValue<T>, context: C) => U,
): Exstream<Promise<Awaited<U>>, C>

Example

const names = exstream(requestPromises)
  .massThen((response) => response.json())
  .resolve(8, true)

Parameters

fn

Type (resolvedValue, context) => URequired

Passed to each input's then(). It may return a value or promise.

Behavior

massThen() does not await, limit, or reorder asynchronous work. It synchronously maps each input x to x.then(fn), so output promise order equals input order while settlement order is unconstrained. Backpressure controls promise objects, not the work already represented by them.

Every input must expose a callable .then(). Context is captured and passed to fn only when it declares a second parameter.

Errors

A missing or invalid .then() becomes a record error through map(). A rejected input bypasses fn and remains a rejected output promise. A throw or rejection from fn rejects that output promise; use resolve() or mapAsync() to turn it into Exstream’s record-error protocol.

Forms

stream.massThen(onFulfilled)
exstream.pipeline().massThen(onFulfilled)
exstream.massThen(onFulfilled, stream)
stream.through(exstream.massThen(onFulfilled))

massCatch(), resolve(), mapAsync()

massThen()