4a3ce4cc1d
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
32 lines
633 B
Markdown
32 lines
633 B
Markdown
---
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category: Utilities
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---
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# isDefined
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Non-nullish checking type guard for Ref.
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## Usage
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```ts
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import { isDefined } from '@vueuse/core'
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const example = ref(Math.random() ? 'example' : undefined) // Ref<string | undefined>
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if (isDefined(example))
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example // Ref<string>
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```
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## Type Declarations
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```ts
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export type IsDefinedReturn = boolean
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export declare function isDefined<T>(
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v: ComputedRef<T>,
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): v is ComputedRef<Exclude<T, null | undefined>>
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export declare function isDefined<T>(
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v: Ref<T>,
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): v is Ref<Exclude<T, null | undefined>>
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export declare function isDefined<T>(v: T): v is Exclude<T, null | undefined>
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```
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