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Add comprehensive reference documentation for: - Vitest: environments, projects/workspaces, type testing, vi utilities - Pinia: HMR, Nuxt integration, SSR setup - Vue: built-in components (Transition, Teleport, Suspense, KeepAlive) and advanced directives
92 lines
2.3 KiB
Markdown
92 lines
2.3 KiB
Markdown
---
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category: '@RxJS'
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---
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# useObservable
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Use an RxJS [`Observable`](https://rxjs.dev/guide/observable), return a `ref`, and automatically unsubscribe from it when the component is unmounted.
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## Usage
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<!-- TODO: import rxjs error if enable twoslash -->
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```ts no-twoslash
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import { useObservable } from '@vueuse/rxjs'
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import { interval } from 'rxjs'
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import { mapTo, scan, startWith } from 'rxjs/operators'
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// setup()
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const count = useObservable(
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interval(1000).pipe(
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mapTo(1),
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startWith(0),
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scan((total, next) => next + total),
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),
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)
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```
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### Initial Value
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You can provide an initial value that will be used before the Observable emits its first value:
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```ts no-twoslash
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import { useObservable } from '@vueuse/rxjs'
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import { interval } from 'rxjs'
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const count = useObservable(
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interval(1000),
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{ initialValue: 0 },
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)
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// count.value is 0 until the first emission
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```
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### Error Handling
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If you want to add custom error handling to an `Observable` that might error, you can supply an optional `onError` configuration. Without this, RxJS will treat any error in the supplied `Observable` as an "unhandled error" and it will be thrown in a new call stack and reported to `window.onerror` (or `process.on('error')` if you happen to be in Node).
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```ts no-twoslash
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import { useObservable } from '@vueuse/rxjs'
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import { interval } from 'rxjs'
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import { map } from 'rxjs/operators'
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// setup()
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const count = useObservable(
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interval(1000).pipe(
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map((n) => {
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if (n === 10)
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throw new Error('oops')
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return n + n
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}),
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),
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{
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onError: (err) => {
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console.log(err.message) // "oops"
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},
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},
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)
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```
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### Options
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| Option | Type | Description |
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| -------------- | -------------------- | ---------------------------------------- |
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| `initialValue` | `T` | Value to use before the Observable emits |
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| `onError` | `(err: any) => void` | Error handler for Observable errors |
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## Type Declarations
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```ts
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export interface UseObservableOptions<I> {
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onError?: (err: any) => void
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/**
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* The value that should be set if the observable has not emitted.
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*/
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initialValue?: I | undefined
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}
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export declare function useObservable<H, I = undefined>(
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observable: Observable<H>,
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options?: UseObservableOptions<I | undefined>,
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): Readonly<Ref<H | I>>
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```
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