Nuxt/docs/3.api/1.composables/use-nuxt-data.md
Sébastien Chopin 3ec108493d
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# `useNuxtData`
`useNuxtData` gives you access to the current cached value of `useAsyncData`, `useLazyAsyncData`, `useFetch` and `useLazyFetch` with explicitly provided key.
## Type
```ts
useNuxtData<DataT = any> (key: string): { data: Ref<DataT | null> }
```
## Examples
### Show stale data while fetching in the background
The example below shows how you can use cached data as a placeholder while the most recent data is being fetched from the server.
```ts [archive.vue]
// We can access same data later using 'posts' key
const { data } = await useFetch('/api/posts', { key: 'posts' })
```
```ts [single.vue]
// Access to the cached value of useFetch in archive.vue
const { data: posts } = useNuxtData('posts')
const { data } = await useFetch(`/api/posts/${postId}`, {
key: `post-${postId}`,
default: () => {
// Find the individual post from the cache and set it as the default value.
return posts.value.find(post => post.id === postId)
}
})
```
### Optimistic Updates
We can leverage the cache to update the UI after a mutation, while the data is being invalidated in the background.
```ts [todos.vue]
// We can access same data later using 'todos' key
const { data } = await useFetch('/api/todos', { key: 'todos' })
```
```ts [add-todo.vue]
const newTodo = ref('')
const previousTodos = ref([])
// Access to the cached value of useFetch in todos.vue
const { data: todos } = useNuxtData('todos')
const { data } = await useFetch('/api/addTodo', {
key: 'addTodo',
method: 'post',
body: {
todo: newTodo.value
},
onRequest () {
previousTodos.value = todos.value // Store the previously cached value to restore if fetch fails.
todos.value.push(newTodo.value) // Optimistically update the todos.
},
onRequestError () {
todos.value = previousTodos.value // Rollback the data if the request failed.
},
async onResponse () {
await refreshNuxtData('todos') // Invalidate todos in the background if the request succeeded.
}
})
```