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Function: reduceAsync()

Returns the result of reducing the asyncIterable using asyncReducer.

Informally, an initial accumulator is created using RawAsyncReducerWithoutFinish.create. Then each value in asyncIterable is added to the accumulator and the current accumulator is updated using RawAsyncReducerWithoutFinish.add. Finally, the resulting accumulator is transformed using RawAsyncReducerWithFinish.finish if specified. Multiple accumulators may be created, added to, and then combined if supported via RawAsyncReducerWithoutFinish.combine and the next value of asyncIterable is ready before promises from RawAsyncReducerWithoutFinish.add resolve.

If asyncReducer is an async optional reducer (no RawAsyncReducerWithoutFinish.create method), then an empty async iterable is returned if asyncIterable is empty. Otherwise, an async iterable containing the result of reducing using the first value of the async iterable as the initial accumulator is returned.

Like Array.prototype.reduce, but for async iterables.

Example​

console.log(
  await pipe(
    asAsync([`Hello`, `World!`, `What`, `an`, `interesting`, `program!`]),
    reduceAsync((a, b) => `${a} ${b}`),
    getAsync,
  ),
)
//=> Hello World! What an interesting program!

console.log(
  await pipe(
    asAsync([`Hello`, `World!`, `What`, `an`, `interesting`, `program!`]),
    reduceAsync({ create: () => ``, add: (a, b) => `${a} ${b}` }),
  ),
)
//=> Hello World! What an interesting program!

Since​

v0.0.1

Call Signature​

reduceAsync<Value, Acc, Finished, This>(asyncReducer, asyncIterable): Promise<Finished>

Type Parameters​

• Value

• Acc

• Finished

• This

Parameters​

asyncReducer​

RawAsyncReducerWithFinish<Value, Acc, Finished, This> | RawReducerWithFinish<Value, Acc, Finished, This>

asyncIterable​

AsyncIterable<Value, any, any>

Returns​

Promise<Finished>

Defined in​

reducers.d.ts:738

Call Signature​

reduceAsync<Value, Acc, Finished, This>(asyncReducer): (asyncIterable) => Promise<Finished>

Type Parameters​

• Value

• Acc

• Finished

• This

Parameters​

asyncReducer​

RawAsyncReducerWithFinish<Value, Acc, Finished, This> | RawReducerWithFinish<Value, Acc, Finished, This>

Returns​

Function

Parameters​

asyncIterable​

AsyncIterable<Value, any, any>

Returns​

Promise<Finished>

Defined in​

reducers.d.ts:744

Call Signature​

reduceAsync<Value, Acc, This>(asyncReducer, asyncIterable): Promise<Acc>

Type Parameters​

• Value

• Acc

• This

Parameters​

asyncReducer​

RawAsyncReducerWithoutFinish<Value, Acc, This> | RawReducerWithoutFinish<Value, Acc, This>

asyncIterable​

AsyncIterable<Value, any, any>

Returns​

Promise<Acc>

Defined in​

reducers.d.ts:750

Call Signature​

reduceAsync<Value, Acc, This>(asyncReducer): (asyncIterable) => Promise<Acc>

Type Parameters​

• Value

• Acc

• This

Parameters​

asyncReducer​

RawAsyncReducerWithoutFinish<Value, Acc, This> | RawReducerWithoutFinish<Value, Acc, This>

Returns​

Function

Parameters​

asyncIterable​

AsyncIterable<Value, any, any>

Returns​

Promise<Acc>

Defined in​

reducers.d.ts:756

Call Signature​

reduceAsync<Value, Finished, This>(asyncReducer, asyncIterable): AsyncOptional<Finished>

Type Parameters​

• Value

• Finished

• This

Parameters​

asyncReducer​

RawAsyncOptionalReducerWithFinish<Value, Finished, This> | RawOptionalReducerWithFinish<Value, Finished, This>

asyncIterable​

AsyncIterable<Value, any, any>

Returns​

AsyncOptional<Finished>

Defined in​

reducers.d.ts:762

Call Signature​

reduceAsync<Value, Finished, This>(asyncReducer): (asyncIterable) => AsyncOptional<Finished>

Type Parameters​

• Value

• Finished

• This

Parameters​

asyncReducer​

RawAsyncOptionalReducerWithFinish<Value, Finished, This> | RawOptionalReducerWithFinish<Value, Finished, This>

Returns​

Function

Parameters​

asyncIterable​

AsyncIterable<Value, any, any>

Returns​

AsyncOptional<Finished>

Defined in​

reducers.d.ts:768

Call Signature​

reduceAsync<Value, This>(asyncReducer, asyncIterable): AsyncOptional<Value>

Type Parameters​

• Value

• This

Parameters​

asyncReducer​

RawAsyncOptionalReducerWithoutFinish<Value, This> | RawOptionalReducerWithoutFinish<Value, This>

asyncIterable​

AsyncIterable<Value, any, any>

Returns​

AsyncOptional<Value>

Defined in​

reducers.d.ts:774

Call Signature​

reduceAsync<Value, This>(asyncReducer): (asyncIterable) => AsyncOptional<Value>

Type Parameters​

• Value

• This

Parameters​

asyncReducer​

RawAsyncOptionalReducerWithoutFinish<Value, This> | RawOptionalReducerWithoutFinish<Value, This>

Returns​

Function

Parameters​

asyncIterable​

AsyncIterable<Value, any, any>

Returns​

AsyncOptional<Value>

Defined in​

reducers.d.ts:780

Call Signature​

reduceAsync<Value>(asyncReducer, asyncIterable): AsyncOptional<Value>

Type Parameters​

• Value

Parameters​

asyncReducer​

AsyncFunctionReducer<Value> | FunctionReducer<Value>

asyncIterable​

AsyncIterable<Value, any, any>

Returns​

AsyncOptional<Value>

Defined in​

reducers.d.ts:786

Call Signature​

reduceAsync<Value>(asyncReducer): (asyncIterable) => AsyncOptional<Value>

Type Parameters​

• Value

Parameters​

asyncReducer​

AsyncFunctionReducer<Value> | FunctionReducer<Value>

Returns​

Function

Parameters​

asyncIterable​

AsyncIterable<Value, any, any>

Returns​

AsyncOptional<Value>

Defined in​

reducers.d.ts:790