Nuxt/docs/content/3.api/1.composables/use-async-data.md
Clément Ollivier e6471689d6
docs(api): add ts signature and js example to use-async-data (#4171)
Co-authored-by: Sébastien Chopin <seb@nuxtjs.com>
Co-authored-by: Anjorin Damilare <damilareanjorin1@gmail.com>
Co-authored-by: Daniel Roe <daniel@roe.dev>
Co-authored-by: Pooya Parsa <pyapar@gmail.com>
2022-04-11 19:24:18 +02:00

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Markdown

# `useAsyncData`
Within your pages, components, and plugins you can use useAsyncData to get access to data that resolves asynchronously.
## Type
```ts [Signature]
function useAsyncData(
key: string,
handler: (nuxtApp?: NuxtApp) => Promise<DataT>,
options?: AsyncDataOptions
): Promise<DataT>
type AsyncDataOptions = {
server?: boolean
lazy?: boolean
default?: () => DataT
transform?: (input: DataT) => DataT
pick?: string[]
watch?: WatchSource[]
initialCache?: boolean
}
type DataT = {
data: Ref<DataT>
pending: Ref<boolean>
refresh: () => Promise<void>
error: Ref<any>
}
```
## Params
* **key**: a unique key to ensure that data fetching can be properly de-duplicated across requests
* **handler**: an asynchronous function that returns a value
* **options**:
* _lazy_: whether to resolve the async function after loading the route, instead of blocking navigation (defaults to `false`)
* _default_: a factory function to set the default value of the data, before the async function resolves - particularly useful with the `lazy: true` option
* _server_: whether to fetch the data on server-side (defaults to `true`)
* _transform_: a function that can be used to alter `handler` function result after resolving
* _pick_: only pick specified keys in this array from `handler` function result
* _watch_: watch reactive sources to auto refresh
* _initialCache_: When set to `false`, will skip payload cache for initial fetch. (defaults to `true`)
Under the hood, `lazy: false` uses `<Suspense>` to block the loading of the route before the data has been fetched. Consider using `lazy: true` and implementing a loading state instead for a snappier user experience.
## Return values
* **data**: the result of the asynchronous function that is passed in
* **pending**: a boolean indicating whether the data is still being fetched
* **refresh**: a function that can be used to refresh the data returned by the `handler` function
* **error**: an error object if the data fetching failed
By default, Nuxt waits until a `refresh` is finished before it can be executed again. Passing `true` as parameter skips that wait.
## Example
```ts
const { data, pending, error, refresh } = useAsyncData(
'mountains',
() => $fetch('https://api.nuxtjs.dev/mountains),
{
pick: ['title']
}
)
```
::ReadMore{link="/guide/features/data-fetching"}
::