mirror of
https://github.com/nuxt/nuxt.git
synced 2024-11-30 09:27:13 +00:00
dc47c64f14
Co-authored-by: Daniel Roe <daniel@roe.dev> Co-authored-by: Sébastien Chopin <seb@nuxtjs.com> Co-authored-by: Pooya Parsa <pooya@pi0.io> Co-authored-by: pooya parsa <pyapar@gmail.com> Co-authored-by: Clément Ollivier <clement.o2p@gmail.com>
85 lines
2.5 KiB
Markdown
85 lines
2.5 KiB
Markdown
---
|
|
navigation.icon: uil:database
|
|
description: Nuxt provides useState composable to create a reactive and SSR-friendly shared state.
|
|
---
|
|
|
|
# State Management
|
|
|
|
Nuxt provides useState composable to create a reactive and SSR-friendly shared state across components.
|
|
|
|
`useState` is an SSR-friendly [`ref`](https://vuejs.org/api/reactivity-core.html#ref) replacement. Its value will be preserved after server-side rendering (during client-side hydration) and shared across all components using a unique key.
|
|
|
|
::ReadMore{link="/api/composables/use-state"}
|
|
::
|
|
|
|
::alert{icon=👉}
|
|
`useState` only works during `setup` or [`Lifecycle Hooks`](https://vuejs.org/api/composition-api-lifecycle.html#composition-api-lifecycle-hooks).
|
|
::
|
|
::alert{type=warning}
|
|
Because the data inside `useState` will be serialized to JSON, it is important that it does not contain anything that cannot be serialized, such as classes, functions or symbols.
|
|
::
|
|
|
|
## Best Practices
|
|
|
|
::alert{type=danger icon=🚨}
|
|
Never define `const state = ref()` outside of `<script setup>` or `setup()` function.<br>
|
|
Such state will be shared across all users visiting your website and can lead to memory leaks!
|
|
::
|
|
::alert{type=success icon=✅}
|
|
Instead use `const useX = () => useState('x')`
|
|
::
|
|
|
|
## Examples
|
|
|
|
### Basic Usage
|
|
|
|
In this example, we use a component-local counter state. Any other component that uses `useState('counter')` shares the same reactive state.
|
|
|
|
```vue [app.vue]
|
|
<script setup>
|
|
const counter = useState('counter', () => Math.round(Math.random() * 1000))
|
|
</script>
|
|
|
|
<template>
|
|
<div>
|
|
Counter: {{ counter }}
|
|
<button @click="counter++">
|
|
+
|
|
</button>
|
|
<button @click="counter--">
|
|
-
|
|
</button>
|
|
</div>
|
|
</template>
|
|
```
|
|
|
|
:LinkExample{link="/examples/composables/use-state"}
|
|
|
|
::ReadMore{link="/api/composables/use-state"}
|
|
::
|
|
|
|
### Advanced
|
|
|
|
In this example, we use a composable that detects the user's default locale from the HTTP request headers and keeps it in a `locale` state.
|
|
|
|
:LinkExample{link="/examples/other/locale"}
|
|
|
|
## Shared State
|
|
|
|
By using [auto-imported composables](/guide/directory-structure/composables) we can define global type-safe states and import them across the app.
|
|
|
|
```ts [composables/states.ts]
|
|
export const useCounter = () => useState<number>('counter', () => 0)
|
|
export const useColor = () => useState<string>('color', () => 'pink')
|
|
```
|
|
|
|
```vue [app.vue]
|
|
<script setup>
|
|
const color = useColor() // Same as useState('color')
|
|
</script>
|
|
|
|
<template>
|
|
<p>Current color: {{ color }}</p>
|
|
</template>
|
|
```
|