# forkJoin

![forkJoin](http://reactivex.io/documentation/operators/images/forkJoin.png)

Runs all observable sequences in parallel and collect their last elements.

## Arguments

1. `args` *(`Arguments` | `Array`)*: An array or arguments of Observable sequences or Promises to collect the last elements for.
2. `resultSelector`: *(`Function`)* - The result selector from all the values produced. If not specified, `forkJoin` will return the results as an array.

## Returns

*(`Observable`)*: An observable sequence with an array collecting the last elements of all the input sequences or the result of the result selector if specified.

## [Example](http://jsbin.com/sudura/2/edit?js,console)

```javascript
/* Using observables and Promises */
var source = Rx.Observable.forkJoin(
    Rx.Observable.return(42),
    Rx.Observable.range(0, 10),
    Rx.Observable.fromArray([1,2,3]),
    RSVP.Promise.resolve(56)
);

var subscription = source.subscribe(
  x => console.log(`onNext: ${x}`),
  e => console.log(`onError: ${e}`),
  () => console.log('onCompleted'));

// => onNext: [42, 9, 3, 56]
// => onCompleted
```

## Example


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://soufatn.gitbook.io/rxjs-book/summary/observable/observable_methods/forkjoin.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.