1---
2category: '@RxJS'
3---
4 
5# toObserver
6 
7Sugar function to convert a `ref` into an RxJS [Observer](https://rxjs.dev/guide/observer).
8 
9## Usage
10 
11<!-- TODO: import rxjs error if enable twoslash -->
12 
13```ts no-twoslash
14import { from, fromEvent, toObserver, useSubscription } from '@vueuse/rxjs'
15import { interval } from 'rxjs'
16import { map, mapTo, startWith, takeUntil, withLatestFrom } from 'rxjs/operators'
17import { shallowRef, useTemplateRef } from 'vue'
18 
19const count = shallowRef(0)
20const button = useTemplateRef('buttonRef')
21 
22useSubscription(
23  interval(1000)
24    .pipe(
25      mapTo(1),
26      takeUntil(fromEvent(button, 'click')),
27      withLatestFrom(from(count).pipe(startWith(0))),
28      map(([curr, total]) => curr + total),
29    )
30    .subscribe(toObserver(count)), // same as ).subscribe(val => (count.value = val))
31)
32```
33 
34## Type Declarations
35 
36```ts
37export declare function toObserver<T>(value: Ref<T>): NextObserver<T>
38```
39