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Kismet Hasanaj
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---
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title: How to lazy load Client Components and libraries
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nav_title: Lazy Loading
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description: Lazy load imported libraries and React Components to improve your application's loading performance.
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---
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{/* The content of this doc is shared between the app and pages router. You can use the `<PagesOnly>Content</PagesOnly>` component to add content that is specific to the Pages Router. Any shared content should not be wrapped in a component. */}
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[Lazy loading](https://developer.mozilla.org/docs/Web/Performance/Lazy_loading) in Next.js helps improve the initial loading performance of an application by decreasing the amount of JavaScript needed to render a route.
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<AppOnly>
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It allows you to defer loading of **Client Components** and imported libraries, and only include them in the client bundle when they're needed. For example, you might want to defer loading a modal until a user clicks to open it.
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There are two ways you can implement lazy loading in Next.js:
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1. Using [Dynamic Imports](#nextdynamic) with `next/dynamic`
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2. Using [`React.lazy()`](https://react.dev/reference/react/lazy) with [Suspense](https://react.dev/reference/react/Suspense)
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By default, Server Components are automatically [code split](https://developer.mozilla.org/docs/Glossary/Code_splitting), and you can use [streaming](/docs/app/guides/streaming) to progressively send pieces of UI from the server to the client. Lazy loading applies to Client Components.
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## `next/dynamic`
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`next/dynamic` is a composite of [`React.lazy()`](https://react.dev/reference/react/lazy) and [Suspense](https://react.dev/reference/react/Suspense). It behaves the same way in the `app` and `pages` directories to allow for incremental migration.
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## Examples
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### Importing Client Components
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```jsx filename="app/page.js"
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'use client'
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import { useState } from 'react'
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import dynamic from 'next/dynamic'
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// Client Components:
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const ComponentA = dynamic(() => import('../components/A'))
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const ComponentB = dynamic(() => import('../components/B'))
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const ComponentC = dynamic(() => import('../components/C'), { ssr: false })
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export default function ClientComponentExample() {
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const [showMore, setShowMore] = useState(false)
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return (
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<div>
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{/* Load immediately, but in a separate client bundle */}
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<ComponentA />
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{/* Load on demand, only when/if the condition is met */}
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{showMore && <ComponentB />}
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<button onClick={() => setShowMore(!showMore)}>Toggle</button>
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{/* Load only on the client side */}
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<ComponentC />
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</div>
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)
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}
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```
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> **Note:** When a Server Component dynamically imports a Client Component, automatic [code splitting](https://developer.mozilla.org/docs/Glossary/Code_splitting) is currently **not** supported.
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### Skipping SSR
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When using `React.lazy()` and Suspense, Client Components will be [prerendered](https://github.com/reactwg/server-components/discussions/4) (SSR) by default.
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> **Note:** `ssr: false` option will only work for Client Components, move it into Client Components ensure the client code-splitting working properly.
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If you want to disable prerendering for a Client Component, you can use the `ssr` option set to `false`:
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```jsx
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const ComponentC = dynamic(() => import('../components/C'), { ssr: false })
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```
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### Importing Server Components
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If you dynamically import a Server Component, only the Client Components that are children of the Server Component will be lazy-loaded - not the Server Component itself.
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It will also help preload the static assets such as CSS when you're using it in Server Components.
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```jsx filename="app/page.js"
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import dynamic from 'next/dynamic'
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// Server Component:
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const ServerComponent = dynamic(() => import('../components/ServerComponent'))
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export default function ServerComponentExample() {
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return (
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<div>
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<ServerComponent />
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</div>
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)
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}
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```
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> **Note:** `ssr: false` option is not supported in Server Components. You will see an error if you try to use it in Server Components.
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> `ssr: false` is not allowed with `next/dynamic` in Server Components. Please move it into a Client Component.
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### Loading External Libraries
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External libraries can be loaded on demand using the [`import()`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Operators/import) function. This example uses the external library `fuse.js` for fuzzy search. The module is only loaded on the client after the user types in the search input.
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```jsx filename="app/page.js"
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'use client'
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import { useState } from 'react'
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const names = ['Tim', 'Joe', 'Bel', 'Lee']
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export default function Page() {
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const [results, setResults] = useState()
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return (
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<div>
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<input
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type="text"
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placeholder="Search"
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onChange={async (e) => {
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const { value } = e.currentTarget
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// Dynamically load fuse.js
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const Fuse = (await import('fuse.js')).default
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const fuse = new Fuse(names)
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setResults(fuse.search(value))
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}}
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/>
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<pre>Results: {JSON.stringify(results, null, 2)}</pre>
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</div>
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)
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}
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```
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### Adding a custom loading component
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```jsx filename="app/page.js"
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'use client'
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import dynamic from 'next/dynamic'
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const WithCustomLoading = dynamic(
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() => import('../components/WithCustomLoading'),
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{
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loading: () => <p>Loading...</p>,
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}
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)
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export default function Page() {
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return (
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<div>
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{/* The loading component will be rendered while <WithCustomLoading/> is loading */}
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<WithCustomLoading />
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</div>
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)
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}
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```
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### Importing Named Exports
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To dynamically import a named export, you can return it from the Promise returned by [`import()`](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Operators/import) function:
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```jsx filename="components/hello.js"
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'use client'
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export function Hello() {
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return <p>Hello!</p>
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}
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```
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```jsx filename="app/page.js"
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import dynamic from 'next/dynamic'
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const ClientComponent = dynamic(() =>
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import('../components/hello').then((mod) => mod.Hello)
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)
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```
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## Magic Comments
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Next.js supports magic comments to control how dynamic imports are handled by the bundler. These comments work with dynamic `import()`, `require()`, `require.resolve()`, and `new Worker()` expressions.
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> **Good to know:** Magic comments do not work with static `import` statements (`import x from 'y'`). They only work with dynamic expressions.
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### `webpackIgnore` / `turbopackIgnore`
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Use these comments to skip bundling a dynamic import. The import expression will be left as-is in the output, useful for runtime-only modules:
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```js
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// Skip bundling - import happens at runtime
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const runtime = await import(/* webpackIgnore: true */ 'runtime-module')
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// Turbopack-specific variant
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const plugin = await import(/* turbopackIgnore: true */ pluginPath)
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// Also works with require
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const mod = require(/* webpackIgnore: true */ 'runtime-module')
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```
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### `turbopackOptional` (Turbopack only)
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Use this comment to suppress build errors when a module might not exist. The import will still throw at runtime if the module is missing:
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```js
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// No build error if './optional-feature' doesn't exist
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// Runtime will throw MODULE_NOT_FOUND if executed
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const feature = await import(/* turbopackOptional: true */ './optional-feature')
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// Also works with require
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const mod = require(/* turbopackOptional: true */ './optional-module')
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```
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This is useful for:
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- Conditional features that may not be installed
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- Plugin systems where modules are optional
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- Gradual migrations where some files may not exist yet
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> **Good to know:** `webpackOptional` is not supported. Use `turbopackOptional` instead when using Turbopack.
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</AppOnly>
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<PagesOnly>
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## `next/dynamic`
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`next/dynamic` is a composite of [`React.lazy()`](https://react.dev/reference/react/lazy) and [Suspense](https://react.dev/reference/react/Suspense). It behaves the same way in the `app` and `pages` directories to allow for incremental migration.
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In the example below, by using `next/dynamic`, the header component will not be included in the page's initial JavaScript bundle. The page will render the Suspense `fallback` first, followed by the `Header` component when the `Suspense` boundary is resolved.
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```jsx
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import dynamic from 'next/dynamic'
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const DynamicHeader = dynamic(() => import('../components/header'), {
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loading: () => <p>Loading...</p>,
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})
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export default function Home() {
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return <DynamicHeader />
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}
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```
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> **Good to know**: In `import('path/to/component')`, the path must be explicitly written. It can't be a template string nor a variable. Furthermore the `import()` has to be inside the `dynamic()` call for Next.js to be able to match webpack bundles / module ids to the specific `dynamic()` call and preload them before rendering. `dynamic()` can't be used inside of React rendering as it needs to be marked in the top level of the module for preloading to work, similar to `React.lazy`.
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## Examples
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### With named exports
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To dynamically import a named export, you can return it from the [Promise](https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Promise) returned by [`import()`](https://github.com/tc39/proposal-dynamic-import#example):
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```jsx filename="components/hello.js"
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export function Hello() {
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return <p>Hello!</p>
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}
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// pages/index.js
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import dynamic from 'next/dynamic'
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const DynamicComponent = dynamic(() =>
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import('../components/hello').then((mod) => mod.Hello)
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)
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```
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### With no SSR
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To dynamically load a component on the client side, you can use the `ssr` option to disable server-rendering. This is useful if an external dependency or component relies on browser APIs like `window`.
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```jsx
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'use client'
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import dynamic from 'next/dynamic'
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const DynamicHeader = dynamic(() => import('../components/header'), {
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ssr: false,
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})
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```
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### With external libraries
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This example uses the external library `fuse.js` for fuzzy search. The module is only loaded in the browser after the user types in the search input.
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```jsx
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import { useState } from 'react'
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const names = ['Tim', 'Joe', 'Bel', 'Lee']
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export default function Page() {
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const [results, setResults] = useState()
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return (
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<div>
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<input
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type="text"
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placeholder="Search"
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onChange={async (e) => {
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const { value } = e.currentTarget
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// Dynamically load fuse.js
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const Fuse = (await import('fuse.js')).default
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const fuse = new Fuse(names)
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setResults(fuse.search(value))
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}}
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/>
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<pre>Results: {JSON.stringify(results, null, 2)}</pre>
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</div>
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)
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}
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```
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</PagesOnly>
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