67 lines
2.1 KiB
Markdown
67 lines
2.1 KiB
Markdown
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---
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title: How to configure Babel in Next.js
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nav_title: Babel
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description: Extend the babel preset added by Next.js with your own configs.
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---
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<details>
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<summary>Examples</summary>
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- [Customizing babel configuration](https://github.com/vercel/next.js/tree/canary/examples/with-custom-babel-config)
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</details>
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Next.js includes the `next/babel` preset to your app, which includes everything needed to compile React applications and server-side code. But if you want to extend the default Babel configs, it's also possible.
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## Adding Presets and Plugins
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To start, you only need to define a `.babelrc` file (or `babel.config.js`) in the root directory of your project. If such a file is found, it will be considered as the _source of truth_, and therefore it needs to define what Next.js needs as well, which is the `next/babel` preset.
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Here's an example `.babelrc` file:
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```json filename=".babelrc"
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{
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"presets": ["next/babel"],
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"plugins": []
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}
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```
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You can [take a look at this file](https://github.com/vercel/next.js/blob/canary/packages/next/src/build/babel/preset.ts) to learn about the presets included by `next/babel`.
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To add presets/plugins **without configuring them**, you can do it this way:
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```json filename=".babelrc"
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{
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"presets": ["next/babel"],
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"plugins": ["@babel/plugin-proposal-do-expressions"]
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}
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```
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## Customizing Presets and Plugins
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To add presets/plugins **with custom configuration**, do it on the `next/babel` preset like so:
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```json filename=".babelrc"
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{
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"presets": [
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[
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"next/babel",
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{
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"preset-env": {},
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"transform-runtime": {},
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"styled-jsx": {},
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"class-properties": {}
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}
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]
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],
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"plugins": []
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}
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```
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To learn more about the available options for each config, visit babel's [documentation](https://babeljs.io/docs/) site.
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> **Good to know**:
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>
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> - Next.js uses the [**current** Node.js version](https://github.com/nodejs/release#release-schedule) for server-side compilations.
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> - The `modules` option on `"preset-env"` should be kept to `false`, otherwise webpack code splitting is turned off.
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