feat(nuxt): deep watch useCookie ref value by default (#9664)

* feat(nuxt): useCookie add deep watch option

* docs(api): useCookie add deepWatch option

* feat(nuxt): useCookie change deepWatch to watch option

* boolean|shallow

* enable watch by default

* docs: fix example

* docs(api): update useCookie example

Co-authored-by: Pooya Parsa <pooya@pi0.io>
Co-authored-by: Daniel Roe <daniel@roe.dev>

docs/content/1.docs/3.api/1.composables/use-cookie.md

@@ -26,15 +26,9 @@ The example below creates a cookie called `counter`. If the cookie doesn't exist
 <template>
   <div>
     <h1>Counter: {{ counter || '-' }}</h1>
-    <button @click="counter = null">
+    <button @click="counter = null">reset</button>
-      reset
+    <button @click="counter--">-</button>
-    </button>
+    <button @click="counter++">+</button>
-    <button @click="counter--">
-      -
-    </button>
-    <button @click="counter++">
-      +
-    </button>
   </div>
 </template>
 
@@ -138,6 +132,71 @@ be returned as the cookie's value.
 
 Specifies a function that returns the cookie's default value. The function can also return a `Ref`.
 
+### `watch`
+
+Specifies the `boolean` or `string` value for [watch](https://vuejs.org/api/reactivity-core.html#watch) cookie ref data.
+
+- `true` - Will watch cookie ref data changes and its nested properties. (default)
+- `shallow` - Will watch cookie ref data changes for only top level properties
+- `false` Will not watch cookie ref data changes.
+
+**Example 1:**
+
+```vue
+<template>
+  <div>User score: {{ user?.score }}</div>
+</template>
+
+<script setup>
+const user = useCookie(
+  'userInfo',
+  {
+    default: () => ({ score: -1 }),
+    watch: false
+  }
+)
+
+if (user.value && user.value !== null) {
+  user.value.score++; // userInfo cookie not update with this change
+}
+</script>
+```
+
+**Example 2:**
+
+```vue
+<template>
+  <div>
+    <h1>List</h1>
+    <pre>{{ list }}</pre>
+    <button @click="add">Add</button>
+    <button @click="save">Save</button>
+  </div>
+</template>
+
+<script setup>
+const list = useCookie(
+  'list',
+  {
+    default: () => [],
+    watch: 'shallow'
+  }
+)
+
+function add() {
+  list.value?.push(Math.round(Math.random() * 1000))
+  // list cookie not update with this change
+}
+
+function save() {
+  if (list.value && list.value !== null) {
+    list.value = [...list.value]
+    // list cookie update with this change
+  }
+}
+</script>
+```
+
 ## Handling Cookies in API Routes
 
 You can use `getCookie` and `setCookie` from [`h3`](https://github.com/unjs/h3) package to set cookies in server API routes.

packages/nuxt/src/app/composables/cookie.ts

@@ -15,12 +15,14 @@ export interface CookieOptions<T = any> extends _CookieOptions {
   decode?(value: string): T
   encode?(value: T): string
   default?: () => T | Ref<T>
+  watch?: boolean | 'shallow'
 }
 
 export interface CookieRef<T> extends Ref<T> {}
 
 const CookieDefaults: CookieOptions<any> = {
   path: '/',
+  watch: true,
   decode: val => destr(decodeURIComponent(val)),
   encode: val => encodeURIComponent(typeof val === 'string' ? val : JSON.stringify(val))
 }
@@ -32,7 +34,12 @@ export function useCookie <T = string | null> (name: string, _opts?: CookieOptio
   const cookie = ref<T | undefined>(cookies[name] as any ?? opts.default?.())
 
   if (process.client) {
-    watch(cookie, () => { writeClientCookie(name, cookie.value, opts as CookieSerializeOptions) })
+    const callback = () => { writeClientCookie(name, cookie.value, opts as CookieSerializeOptions) }
+    if (opts.watch) {
+      watch(cookie, callback, { deep: opts.watch !== 'shallow' })
+    } else {
+      callback()
+    }
   } else if (process.server) {
     const nuxtApp = useNuxtApp()
     const writeFinalCookieValue = () => {