Nuxt/docs/2.guide/2.directory-structure/1.components.md
Sébastien Chopin f26a801775
docs: update to new website (#23743)
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: Daniel Roe <daniel@roe.dev>
2023-10-18 12:59:43 +02:00

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components components/ The components/ directory is where you put all your Vue components. i-ph-folder-duotone

Nuxt automatically imports any components in this directory (along with components that are registered by any modules you may be using).

| components/
--| AppHeader.vue
--| AppFooter.vue
<template>
  <div>
    <AppHeader />
    <NuxtPage />
    <AppFooter />
  </div>
</template>

Component Names

If you have a component in nested directories such as:

| components/
--| base/
----| foo/
------| Button.vue

... then the component's name will be based on its own path directory and filename, with duplicate segments being removed. Therefore, the component's name will be:

<BaseFooButton />

::callout For clarity, we recommend that the component's filename matches its name. So, in the example above, you could rename Button.vue to be BaseFooButton.vue. ::

If you want to auto-import components based only on its name, not path, then you need to set pathPrefix option to false using extended form of the configuration object:

export default defineNuxtConfig({
  components: [
    {
      path: '~/components',
+     pathPrefix: false,
    },
  ],
});

This registers the components using the same strategy as used in Nuxt 2. For example, ~/components/Some/MyComponent.vue will be usable as <MyComponent> and not <SomeMyComponent>.

Dynamic Components

If you want to use the Vue <component :is="someComputedComponent">{lang=vue} syntax, you need to use the resolveComponent helper provided by Vue or import the component directly from #components and pass it into is prop.

For example:

<script setup lang="ts">
import { SomeComponent } from '#components'

const MyButton = resolveComponent('MyButton')
</script>

<template>
  <component :is="clickable ? MyButton : 'div'" />
  <component :is="SomeComponent" />
</template>

::callout If you are using resolveComponent to handle dynamic components, make sure not to insert anything but the name of the component, which must be a string and not a variable. ::

Alternatively, though not recommended, you can register all your components globally, which will create async chunks for all your components and make them available throughout your application.

  export default defineNuxtConfig({
    components: {
+     global: true,
+     dirs: ['~/components']
    },
  })

You can also selectively register some components globally by placing them in a ~/components/global directory.

::callout The global option can also be set per component directory. ::

Dynamic Imports

To dynamically import a component (also known as lazy-loading a component) all you need to do is add the Lazy prefix to the component's name. This is particularly useful if the component is not always needed.

By using the Lazy prefix you can delay loading the component code until the right moment, which can be helpful for optimizing your JavaScript bundle size.

<script setup>
const show = ref(false)
</script>

<template>
  <div>
    <h1>Mountains</h1>
    <LazyMountainsList v-if="show" />
    <button v-if="!show" @click="show = true">Show List</button>
  </div>
</template>

Direct Imports

You can also explicitly import components from #components if you want or need to bypass Nuxt's auto-importing functionality.

<script setup lang="ts">
import { NuxtLink, LazyMountainsList } from '#components'

const show = ref(false)
</script>

<template>
  <div>
    <h1>Mountains</h1>
    <LazyMountainsList v-if="show" />
    <button v-if="!show" @click="show = true">Show List</button>
    <NuxtLink to="/">Home</NuxtLink>
  </div>
</template>

Custom Directories

By default, only the ~/components directory is scanned. If you want to add other directories, or change how the components are scanned within a subfolder of this directory, you can add additional directories to the configuration:

export default defineNuxtConfig({
  components: [
    // ~/calendar-module/components/event/Update.vue => <EventUpdate />
    { path: '~/calendar-module/components' },

    // ~/user-module/components/account/UserDeleteDialog.vue => <UserDeleteDialog />
    { path: '~/user-module/components', pathPrefix: false },

    // ~/components/special-components/Btn.vue => <SpecialBtn />
    { path: '~/components/special-components', prefix: 'Special' },

    // It's important that this comes last if you have overrides you wish to apply
    // to sub-directories of `~/components`.
    //
    // ~/components/Btn.vue => <Btn />
    // ~/components/base/Btn.vue => <BaseBtn />
    '~/components'
  ]
})

::callout Any nested directories need to be added first as they are scanned in order. ::

Component Extensions

By default, any file with an extension specified in the extensions key of nuxt.config.ts is treated as a component. If you need to restrict the file extensions that should be registered as components, you can use the extended form of the components directory declaration and its extensions key:

export default defineNuxtConfig({
  components: [
    {
      path: '~/components',
+     extensions: ['.vue'],
    }
  ]
})

Client Components

If a component is meant to be rendered only client-side, you can add the .client suffix to your component.

| components/
--| Comments.client.vue
<template>
  <div>
    <!-- this component will only be rendered on client side -->
    <Comments />
  </div>
</template>

::callout This feature only works with Nuxt auto-imports and #components imports. Explicitly importing these components from their real paths does not convert them into client-only components. ::

::callout{color="amber" icon="i-ph-warning-duotone"} .client components are rendered only after being mounted. To access the rendered template using onMounted(), add await nextTick() in the callback of the onMounted() hook. ::

Server Components

Server components allow server-rendering individual components within your client-side apps. It's possible to use server components within Nuxt, even if you are generating a static site. That makes it possible to build complex sites that mix dynamic components, server-rendered HTML and even static chunks of markup.

Server components can either be used on their own or paired with a client component.

::callout{color="blue" icon="i-ph-video-duotone" to="https://www.youtube.com/watch?v=u1yyXe86xJM" target="_blank"} Watch Learn Vue video about Nuxt Server Components. ::

::callout{color="blue" icon="i-ph-article-duotone" to="https://roe.dev/blog/nuxt-server-components" target="_blank"} Read Daniel Roe's guide to Nuxt server components ::

Standalone server components

Standalone server components will always be rendered on the server, also known as Islands components.

When their props update, this will result in a network request that will update the rendered HTML in-place.

Server components are currently experimental and in order to use them, you need to enable the 'component islands' feature in your nuxt.config:

export default defineNuxtConfig({
  experimental: {
    componentIslands: true
  }
})

Now you can register server-only components with the .server suffix and use them anywhere in your application automatically.

| components/
--| HighlightedMarkdown.server.vue
<template>
  <div>
    <!--
      this will automatically be rendered on the server, meaning your markdown parsing + highlighting
      libraries are not included in your client bundle.
     -->
    <HighlightedMarkdown markdown="# Headline" />
  </div>
</template>

Server-only components use <NuxtIsland> under the hood, meaning that lazy prop and #fallback slot are both passed down to it.

Server Component Context

When rendering a server-only or island component, <NuxtIsland> makes a fetch request which comes back with a NuxtIslandResponse. (This is an internal request if rendered on the server, or a request that you can see in the network tab if it's rendering on client-side navigation.)

This means:

  • A new Vue app will be created server-side to create the NuxtIslandResponse.
  • A new 'island context' will be created while rendering the component.
  • You can't access the 'island context' from the rest of your app and you can't access the context of the rest of your app from the island component. In other words, the server component or island is isolated from the rest of your app.
  • Your plugins will run again when rendering the island, unless they have env: { islands: false } set (which you can do in an object-syntax plugin).

Within an island component, you can access its island context through nuxtApp.ssrContext.islandContext. Note that while island components are still marked as experimental, the format of this context may change.

::callout Slots can be interactive and are wrapped within a <div> with display: contents; ::

Paired with a Client component

In this case, the .server + .client components are two 'halves' of a component and can be used in advanced use cases for separate implementations of a component on server and client side.

| components/
--| Comments.client.vue
--| Comments.server.vue
<template>
  <div>
    <!-- this component will render Comments.server on the server then Comments.client once mounted in the browser -->
    <Comments />
  </div>
</template>

<ClientOnly> Component

Nuxt provides the <ClientOnly> component for purposely rendering a component only on client side.

<template>
  <div>
    <Sidebar />
    <ClientOnly>
      <!-- this component will only be rendered on client-side -->
      <Comments />
    </ClientOnly>
  </div>
</template>

Use a slot as fallback until <ClientOnly> is mounted on client side.

<template>
  <div>
    <Sidebar />
    <!-- This renders the "span" element on the server side -->
    <ClientOnly fallbackTag="span">
      <!-- this component will only be rendered on client side -->
      <Comments />
      <template #fallback>
        <!-- this will be rendered on server side -->
        <p>Loading comments...</p>
      </template>
    </ClientOnly>
  </div>
</template>

<DevOnly> Component

Nuxt provides the <DevOnly> component to render a component only during development.

The content will not be included in production builds and tree-shaken.

<template>
  <div>
    <Sidebar />
    <DevOnly>
      <!-- this component will only be rendered during development -->
      <LazyDebugBar />

      <!-- if you ever require to have a replacement during production -->
      <!-- be sure to test these using `nuxt preview` -->
      <template #fallback>
        <div><!-- empty div for flex.justify-between --></div>
      </template>
    </DevOnly>
  </div>
</template>

<NuxtClientFallback> Component

Nuxt provides the <NuxtClientFallback> component to render its content on the client if any of its children trigger an error in SSR. You can specify a fallbackTag to make it render a specific tag if it fails to render on the server.

<template>
  <div>
    <Sidebar />
    <!-- this component will be rendered on client-side -->
    <NuxtClientFallback fallback-tag="span">
      <Comments />
      <BrokeInSSR />
    </NuxtClientFallback>
  </div>
</template>

Library Authors

Making Vue component libraries with automatic tree-shaking and component registration is super easy

You can use the components:dirs hook to extend the directory list without requiring user configuration in your Nuxt module.

Imagine a directory structure like this:

| node_modules/
---| awesome-ui/
------| components/
---------| Alert.vue
---------| Button.vue
------| nuxt.js
| pages/
---| index.vue
| nuxt.config.js

Then in awesome-ui/nuxt.js you can use the components:dirs hook:

import { defineNuxtModule, createResolver } from '@nuxt/kit'

export default defineNuxtModule({
  hooks: {
    'components:dirs': (dirs) => {
      const { resolve } = createResolver(import.meta.url)
      // Add ./components dir to the list
      dirs.push({
        path: resolve('./components'),
        prefix: 'awesome'
      })
    }
  }
})

That's it! Now in your project, you can import your UI library as a Nuxt module in your nuxt.config file:

export default defineNuxtConfig({
  modules: ['awesome-ui/nuxt']
})

... and directly use the module components (prefixed with awesome-) in our pages/index.vue:

<template>
  <div>
    My <AwesomeButton>UI button</AwesomeButton>!
    <awesome-alert>Here's an alert!</awesome-alert>
  </div>
</template>

It will automatically import the components only if used and also support HMR when updating your components in node_modules/awesome-ui/components/.

:link-example{to="/docs/examples/features/auto-imports"}