mirror of https://github.com/nuxt/nuxt.git
223 lines
7.2 KiB
Markdown
223 lines
7.2 KiB
Markdown
---
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title: 'useCookie'
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description: useCookie is an SSR-friendly composable to read and write cookies.
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links:
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- label: Source
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icon: i-simple-icons-github
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to: https://github.com/nuxt/nuxt/blob/main/packages/nuxt/src/app/composables/cookie.ts
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size: xs
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---
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Within your pages, components and plugins you can use `useCookie`, an SSR-friendly composable to read and write cookies.
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```ts
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const cookie = useCookie(name, options)
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```
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::callout
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`useCookie` ref will automatically serialize and deserialize cookie value to JSON.
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::
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## Example
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The example below creates a cookie called `counter`. If the cookie doesn't exist, it is initially set to a random value. Whenever we update the `counter` variable, the cookie will be updated accordingly.
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```vue [app.vue]
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<script setup lang="ts">
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const counter = useCookie('counter')
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counter.value = counter.value || Math.round(Math.random() * 1000)
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</script>
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<template>
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<div>
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<h1>Counter: {{ counter || '-' }}</h1>
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<button @click="counter = null">reset</button>
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<button @click="counter--">-</button>
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<button @click="counter++">+</button>
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</div>
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</template>
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```
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:link-example{to="/docs/examples/advanced/use-cookie"}
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## Options
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Cookie composable accepts several options which let you modify the behavior of cookies.
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Most of the options will be directly passed to the [cookie](https://github.com/jshttp/cookie) package.
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### `maxAge` / `expires`
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Use these options to set the expiration of the cookie.
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`maxAge`: Specifies the `number` (in seconds) to be the value for the [`Max-Age` `Set-Cookie` attribute](https://tools.ietf.org/html/rfc6265#section-5.2.2).
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The given number will be converted to an integer by rounding down. By default, no maximum age is set.
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`expires`: Specifies the `Date` object to be the value for the [`Expires` `Set-Cookie` attribute](https://tools.ietf.org/html/rfc6265#section-5.2.1).
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By default, no expiration is set. Most clients will consider this a "non-persistent cookie" and
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will delete it on a condition like exiting a web browser application.
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::callout
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The [cookie storage model specification](https://tools.ietf.org/html/rfc6265#section-5.3) states that if both `expires` and
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`maxAge` is set, then `maxAge` takes precedence, but not all clients may obey this,
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so if both are set, they should point to the same date and time!
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::
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::callout
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If neither of `expires` and `maxAge` is set, the cookie will be session-only and removed when the user closes their browser.
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::
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### `httpOnly`
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Specifies the `boolean` value for the [`HttpOnly` `Set-Cookie` attribute](https://tools.ietf.org/html/rfc6265#section-5.2.6). When truthy,
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the `HttpOnly` attribute is set; otherwise it is not. By default, the `HttpOnly` attribute is not set.
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::callout
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Be careful when setting this to `true`, as compliant clients will not allow client-side
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JavaScript to see the cookie in `document.cookie`.
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::
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### `secure`
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Specifies the `boolean` value for the [`Secure` `Set-Cookie` attribute](https://tools.ietf.org/html/rfc6265#section-5.2.5). When truthy,
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the `Secure` attribute is set; otherwise it is not. By default, the `Secure` attribute is not set.
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::callout
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Be careful when setting this to `true`, as compliant clients will not send the cookie back to
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the server in the future if the browser does not have an HTTPS connection. This can lead to hydration errors.
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::
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### `domain`
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Specifies the value for the [`Domain` `Set-Cookie` attribute](https://tools.ietf.org/html/rfc6265#section-5.2.3). By default, no domain is set, and most clients will consider applying the cookie only to the current domain.
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### `path`
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Specifies the value for the [`Path` `Set-Cookie` attribute](https://tools.ietf.org/html/rfc6265#section-5.2.4). By default, the path is considered the ["default path"](https://tools.ietf.org/html/rfc6265#section-5.1.4).
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### `sameSite`
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Specifies the `boolean` or `string` value for the [`SameSite` `Set-Cookie` attribute](https://tools.ietf.org/html/draft-ietf-httpbis-rfc6265bis-03#section-4.1.2.7).
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- `true` will set the `SameSite` attribute to `Strict` for strict same-site enforcement.
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- `false` will not set the `SameSite` attribute.
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- `'lax'` will set the `SameSite` attribute to `Lax` for lax same-site enforcement.
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- `'none'` will set the `SameSite` attribute to `None` for an explicit cross-site cookie.
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- `'strict'` will set the `SameSite` attribute to `Strict` for strict same-site enforcement.
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More information about the different enforcement levels can be found in [the specification](https://tools.ietf.org/html/draft-ietf-httpbis-rfc6265bis-03#section-4.1.2.7).
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### `encode`
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Specifies a function that will be used to encode a cookie's value. Since the value of a cookie
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has a limited character set (and must be a simple string), this function can be used to encode
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a value into a string suited for a cookie's value.
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The default encoder is the `JSON.stringify` + `encodeURIComponent`.
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### `decode`
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Specifies a function that will be used to decode a cookie's value. Since the value of a cookie
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has a limited character set (and must be a simple string), this function can be used to decode
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a previously encoded cookie value into a JavaScript string or other object.
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The default decoder is `decodeURIComponent` + [destr](https://github.com/unjs/destr).
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::callout
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If an error is thrown from this function, the original, non-decoded cookie value will
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be returned as the cookie's value.
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::
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### `default`
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Specifies a function that returns the cookie's default value. The function can also return a `Ref`.
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### `readonly`
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Allows _accessing_ a cookie value without the ability to set it.
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### `watch`
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Specifies the `boolean` or `string` value for [watch](https://vuejs.org/api/reactivity-core.html#watch) cookie ref data.
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- `true` - Will watch cookie ref data changes and its nested properties (default).
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- `shallow` - Will watch cookie ref data changes for only top level properties
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- `false` - Will not watch cookie ref data changes.
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**Example 1:**
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```vue
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<script setup lang="ts">
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const user = useCookie(
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'userInfo',
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{
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default: () => ({ score: -1 }),
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watch: false
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}
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)
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if (user.value && user.value !== null) {
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user.value.score++; // userInfo cookie not update with this change
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}
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</script>
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<template>
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<div>User score: {{ user?.score }}</div>
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</template>
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```
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**Example 2:**
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```vue
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<script setup lang="ts">
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const list = useCookie(
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'list',
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{
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default: () => [],
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watch: 'shallow'
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}
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)
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function add() {
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list.value?.push(Math.round(Math.random() * 1000))
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// list cookie not update with this change
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}
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function save() {
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if (list.value && list.value !== null) {
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list.value = [...list.value]
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// list cookie update with this change
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}
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}
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</script>
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<template>
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<div>
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<h1>List</h1>
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<pre>{{ list }}</pre>
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<button @click="add">Add</button>
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<button @click="save">Save</button>
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</div>
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</template>
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```
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## Cookies in API Routes
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You can use `getCookie` and `setCookie` from [`h3`](https://github.com/unjs/h3) package to set cookies in server API routes.
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```ts [server/api/counter.ts]
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export default defineEventHandler(event => {
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// Read counter cookie
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let counter = getCookie(event, 'counter') || 0
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// Increase counter cookie by 1
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setCookie(event, 'counter', ++counter)
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// Send JSON response
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return { counter }
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})
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```
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:link-example{to="/docs/examples/advanced/use-cookie"}
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