---
category: '@RxJS'
---

# toObserver

Sugar function to convert a `ref` into an RxJS [Observer](https://rxjs.dev/guide/observer).

## Usage

<!-- TODO: import rxjs error if enable twoslash -->

```ts no-twoslash
import { from, fromEvent, toObserver, useSubscription } from '@vueuse/rxjs';
import { interval } from 'rxjs';
import { map, mapTo, startWith, takeUntil, withLatestFrom } from 'rxjs/operators';
import { shallowRef, useTemplateRef } from 'vue';

const count = shallowRef(0);
const button = useTemplateRef('buttonRef');

useSubscription(
  interval(1000)
    .pipe(
      mapTo(1),
      takeUntil(fromEvent(button, 'click')),
      withLatestFrom(from(count).pipe(startWith(0))),
      map(([curr, total]) => curr + total),
    )
    .subscribe(toObserver(count)), // same as ).subscribe(val => (count.value = val))
);
```

## Type Declarations

```ts
export declare function toObserver<T>(value: Ref<T>): NextObserver<T>;
```
