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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
81 lines
2.4 KiB
Markdown
81 lines
2.4 KiB
Markdown
---
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category: '@RxJS'
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---
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# from / fromEvent
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Wrappers around RxJS's [`from()`](https://rxjs.dev/api/index/function/from) and [`fromEvent()`](https://rxjs.dev/api/index/function/fromEvent) to allow them to accept `ref`s.
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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 { from, fromEvent, toObserver, useSubscription } from '@vueuse/rxjs'
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import { interval } from 'rxjs'
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import { map, mapTo, takeUntil, withLatestFrom } from 'rxjs/operators'
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import { shallowRef, useTemplateRef } from 'vue'
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const count = shallowRef(0)
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const button = useTemplateRef('buttonRef')
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useSubscription(
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interval(1000)
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.pipe(
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mapTo(1),
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takeUntil(fromEvent(button, 'click')),
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withLatestFrom(from(count, {
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immediate: true,
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deep: false,
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})),
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map(([curr, total]) => curr + total),
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)
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.subscribe(toObserver(count)), // same as ).subscribe(val => (count.value = val))
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)
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```
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## from
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The `from` function can accept either a standard RxJS `ObservableInput` or a Vue `ref`. When passed a ref, it creates an Observable that emits whenever the ref's value changes.
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### Watch Options
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When using `from` with a ref, you can pass Vue's `WatchOptions`:
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| Option | Type | Description |
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| ----------- | --------------------------- | ---------------------------------- |
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| `immediate` | `boolean` | Emit the current value immediately |
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| `deep` | `boolean` | Deeply watch nested objects |
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| `flush` | `'pre' \| 'post' \| 'sync'` | Timing of the callback flush |
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## fromEvent
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The `fromEvent` function extends RxJS's `fromEvent` to accept a ref to an element. When the ref's value changes (e.g., after the component mounts), it automatically subscribes to the new element.
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```ts no-twoslash
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import { fromEvent, useSubscription } from '@vueuse/rxjs'
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import { useTemplateRef } from 'vue'
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const button = useTemplateRef('buttonRef')
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// Will automatically subscribe when the button element becomes available
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useSubscription(
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fromEvent(button, 'click').subscribe(() => {
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console.log('clicked!')
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})
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)
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```
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## Type Declarations
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```ts
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export declare function from<T>(
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value: ObservableInput<T> | Ref<T>,
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watchOptions?: WatchOptions,
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): Observable<T>
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export declare function fromEvent<T extends HTMLElement | null>(
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value: MaybeRef<T>,
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event: string,
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): Observable<Event>
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```
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