---
title: How to load and optimize scripts
nav_title: Scripts
description: Optimize 3rd party scripts with the built-in Script component.
related:
title: API Reference
description: Learn more about the next/script API.
links:
- app/api-reference/components/script
---
{/* The content of this doc is shared between the app and pages router. You can use the `Content` component to add content that is specific to the Pages Router. Any shared content should not be wrapped in a component. */}
### Layout Scripts
To load a third-party script for multiple routes, import `next/script` and include the script directly in your layout component:
```tsx filename="app/dashboard/layout.tsx" switcher
import Script from 'next/script'
export default function DashboardLayout({
children,
}: {
children: React.ReactNode
}) {
return (
<>
)
}
```
```jsx filename="app/dashboard/layout.js" switcher
import Script from 'next/script'
export default function DashboardLayout({ children }) {
return (
<>
)
}
```
The third-party script is fetched when the folder route (e.g. `dashboard/page.js`) or any nested route (e.g. `dashboard/settings/page.js`) is accessed by the user. Next.js will ensure the script will **only load once**, even if a user navigates between multiple routes in the same layout.
### Application Scripts
To load a third-party script for all routes, import `next/script` and include the script directly in your root layout:
```tsx filename="app/layout.tsx" switcher
import Script from 'next/script'
export default function RootLayout({
children,
}: {
children: React.ReactNode
}) {
return (
{children}
)
}
```
```jsx filename="app/layout.js" switcher
import Script from 'next/script'
export default function RootLayout({ children }) {
return (
{children}
)
}
```
To load a third-party script for all routes, import `next/script` and include the script directly in your custom `_app`:
```jsx filename="pages/_app.js"
import Script from 'next/script'
export default function MyApp({ Component, pageProps }) {
return (
<>
)
}
```
This script will load and execute when _any_ route in your application is accessed. Next.js will ensure the script will **only load once**, even if a user navigates between multiple pages.
> **Recommendation**: We recommend only including third-party scripts in specific pages or layouts in order to minimize any unnecessary impact to performance.
### Strategy
Although the default behavior of `next/script` allows you to load third-party scripts in any page or layout, you can fine-tune its loading behavior by using the `strategy` property:
- `beforeInteractive`: Load the script before any Next.js code and before any page hydration occurs.
- `afterInteractive`: (**default**) Load the script early but after some hydration on the page occurs.
- `lazyOnload`: Load the script later during browser idle time.
- `worker`: (experimental) Load the script in a web worker.
Refer to the [`next/script`](/docs/app/api-reference/components/script#strategy) API reference documentation to learn more about each strategy and their use cases.
### Offloading Scripts To A Web Worker (experimental)
> **Warning:** The `worker` strategy is not yet stable and does not yet work with the App Router. Use with caution.
Scripts that use the `worker` strategy are offloaded and executed in a web worker with [Partytown](https://partytown.builder.io/). This can improve the performance of your site by dedicating the main thread to the rest of your application code.
This strategy is still experimental and can only be used if the `nextScriptWorkers` flag is enabled in `next.config.js`:
```js filename="next.config.js"
module.exports = {
experimental: {
nextScriptWorkers: true,
},
}
```
Then, run `next` (normally `npm run dev` or `yarn dev`) and Next.js will guide you through the installation of the required packages to finish the setup:
```bash filename="Terminal"
npm run dev
```
You'll see instructions like these: Please install Partytown by running `npm install @builder.io/partytown`
Once setup is complete, defining `strategy="worker"` will automatically instantiate Partytown in your application and offload the script to a web worker.
```tsx filename="pages/home.tsx" switcher
import Script from 'next/script'
export default function Home() {
return (
<>
)
}
```
```jsx filename="pages/home.js" switcher
import Script from 'next/script'
export default function Home() {
return (
<>
)
}
```
There are a number of trade-offs that need to be considered when loading a third-party script in a web worker. Please see Partytown's [tradeoffs](https://partytown.builder.io/trade-offs) documentation for more information.
#### Using custom Partytown configuration
Although the `worker` strategy does not require any additional configuration to work, Partytown supports the use of a config object to modify some of its settings, including enabling `debug` mode and forwarding events and triggers.
If you would like to add additional configuration options, you can include it within the `` component used in a [custom `_document.js`](/docs/pages/building-your-application/routing/custom-document):
```jsx filename="_pages/document.jsx"
import { Html, Head, Main, NextScript } from 'next/document'
export default function Document() {
return (
)
}
```
In order to modify Partytown's configuration, the following conditions must be met:
1. The `data-partytown-config` attribute must be used in order to overwrite the default configuration used by Next.js
2. Unless you decide to save Partytown's library files in a separate directory, the `lib: "/_next/static/~partytown/"` property and value must be included in the configuration object in order to let Partytown know where Next.js stores the necessary static files.
> **Note**: If you are using an [asset prefix](/docs/pages/api-reference/config/next-config-js/assetPrefix) and would like to modify Partytown's default configuration, you must include it as part of the `lib` path.
Take a look at Partytown's [configuration options](https://partytown.builder.io/configuration) to see the full list of other properties that can be added.
### Inline Scripts
Inline scripts, or scripts not loaded from an external file, are also supported by the Script component. They can be written by placing the JavaScript within curly braces:
```jsx
```
Or by using the `dangerouslySetInnerHTML` property:
```jsx
```
> **Warning**: An `id` property must be assigned for inline scripts in order for Next.js to track and optimize the script.
### Executing Additional Code
Event handlers can be used with the Script component to execute additional code after a certain event occurs:
- `onLoad`: Execute code after the script has finished loading.
- `onReady`: Execute code after the script has finished loading and every time the component is mounted.
- `onError`: Execute code if the script fails to load.
These handlers will only work when `next/script` is imported and used inside of a [Client Component](/docs/app/getting-started/server-and-client-components) where `"use client"` is defined as the first line of code:
```tsx filename="app/page.tsx" switcher
'use client'
import Script from 'next/script'
export default function Page() {
return (
<>