feat(nuxt): tryUseNuxtApp composable (#25031)

docs/2.guide/3.going-further/1.internals.md

@@ -28,6 +28,8 @@ You can think of it as **Runtime Core**.
 This context can be accessed using [`useNuxtApp()`](/docs/api/composables/use-nuxt-app) composable within Nuxt plugins and `<script setup>` and vue composables.
 Global usage is possible for the browser but not on the server, to avoid sharing context between users.
 
+Since [`useNuxtApp`](/docs/api/composables/use-nuxt-app) throws an exception if context is currently unavailable, if your composable does not always require `nuxtApp`, you can use [`tryUseNuxtApp`](/docs/api/composables/use-nuxt-app#tryusenuxtapp) instead, which will return `null` instead of throwing an exception.
+
 To extend the `nuxtApp` interface and hook into different stages or access contexts, we can use [Nuxt Plugins](/docs/guide/directory-structure/plugins).
 
 Check [Nuxt App](/docs/api/composables/use-nuxt-app) for more information about this interface.

docs/2.guide/3.going-further/6.nuxt-app.md

@@ -30,6 +30,8 @@ export function useMyComposable () {
 }
 ```
 
+If your composable does not always need `nuxtApp` or you simply want to check if it is present or not, since [`useNuxtApp`](/docs/api/composables/use-nuxt-app) throws an exception, you can use [`tryUseNuxtApp`](/docs/api/composables/use-nuxt-app#tryusenuxtapp) instead.
+
 Plugins also receive `nuxtApp` as the first argument for convenience.
 
 :read-more{to="/docs/guide/directory-structure/plugins"}

docs/3.api/2.composables/use-nuxt-app.md

@@ -16,6 +16,8 @@ const nuxtApp = useNuxtApp()
 </script>
 ```
 
+If runtime context is unavailable in your scope, `useNuxtApp` will throw an exception when called. You can use [`tryUseNuxtApp`](#tryusenuxtapp) instead for composables that do not require `nuxtApp`, or to simply check if context is available or not without an exception.
+
 ## Methods
 
 ### `provide (name, value)`
@@ -257,3 +259,22 @@ Native async context support works currently in Bun and Node.
 ::
 
 :read-more{to="/docs/guide/going-further/experimental-features#asynccontext"}
+
+## tryUseNuxtApp
+
+This function works exactly the same as `useNuxtApp`, but returns `null` if context is unavailable instead of throwing an exception.
+
+You can use it for composables that do not require `nuxtApp`, or to simply check if context is available or not without an exception.
+
+Example usage:
+
+```ts [composable.ts]
+export function useStandType() {
+  // Always works on the client
+  if (tryUseNuxtApp()) {
+    return useRuntimeConfig().public.STAND_TYPE
+  } else {
+    return process.env.STAND_TYPE
+  }
+}
+```

packages/nuxt/src/app/nuxt.ts

@@ -439,15 +439,29 @@ export function callWithNuxt<T extends (...args: any[]) => any> (nuxt: NuxtApp |
 /*@__NO_SIDE_EFFECTS__*/
 /**
  * Returns the current Nuxt instance.
+ * 
+ * Returns `null` if Nuxt instance is unavailable.
  */
-export function useNuxtApp (): NuxtApp {
+export function tryUseNuxtApp (): NuxtApp | null {
   let nuxtAppInstance
   if (hasInjectionContext()) {
     nuxtAppInstance = getCurrentInstance()?.appContext.app.$nuxt
   }
 
   nuxtAppInstance = nuxtAppInstance || nuxtAppCtx.tryUse()
 
+  return nuxtAppInstance || null
+}
+
+/*@__NO_SIDE_EFFECTS__*/
+/**
+ * Returns the current Nuxt instance.
+ * 
+ * Throws an error if Nuxt instance is unavailable.
+ */
+export function useNuxtApp (): NuxtApp {
+  const nuxtAppInstance = tryUseNuxtApp()
+
   if (!nuxtAppInstance) {
     if (import.meta.dev) {
       throw new Error('[nuxt] A composable that requires access to the Nuxt instance was called outside of a plugin, Nuxt hook, Nuxt middleware, or Vue setup function. This is probably not a Nuxt bug. Find out more at `https://nuxt.com/docs/guide/concepts/auto-imports#vue-and-nuxt-composables`.')

packages/nuxt/src/imports/presets.ts

@@ -18,7 +18,7 @@ const granularAppPresets: InlinePreset[] = [
     imports: ['defineNuxtLink']
   },
   {
-    imports: ['useNuxtApp', 'defineNuxtPlugin', 'definePayloadPlugin', 'useRuntimeConfig', 'defineAppConfig'],
+    imports: ['useNuxtApp', 'tryUseNuxtApp', 'defineNuxtPlugin', 'definePayloadPlugin', 'useRuntimeConfig', 'defineAppConfig'],
     from: '#app/nuxt'
   },
   {

test/basic.test.ts

@@ -2130,6 +2130,12 @@ describe.skipIf(process.env.TEST_CONTEXT !== 'async')('Async context', () => {
   })
 })
 
+describe.skipIf(process.env.TEST_CONTEXT === 'async')('Async context', () => {
+  it('should be unavailable', async () => {
+    expect(await $fetch('/async-context')).toContain('"hasApp": false')
+  })
+})
+
 describe.skipIf(isWindows)('useAsyncData', () => {
   it('works after useNuxtData call', async () => {
     const page = await createPage('/useAsyncData/nuxt-data')

test/fixtures/basic/composables/async-context.ts

@@ -12,7 +12,7 @@ async function fn1 () {
 
 async function fn2 () {
   await delay()
-  const app = useNuxtApp()
+  const app = tryUseNuxtApp()
   return {
     hasApp: !!app
   }