Next.js + Less
Import .less files in your Next.js project
Installation
npm install --save @zeit/next-less less
or
yarn add @zeit/next-less less
Usage
The stylesheet is compiled to .next/static/css. Next.js will automatically add the css file to the HTML.
In production a chunk hash is added so that styles are updated when a new version of the stylesheet is deployed.
Without CSS modules
Create a next.config.js in your project
// next.config.js
const withLess = require('@zeit/next-less')
module.exports = withLess()Create a Less file styles.less
@font-size: 50px;
.example {
font-size: @font-size;
}Create a page file pages/index.js
import "../styles.less"
export default () => <div className="example">Hello World!</div>With CSS modules
// next.config.js
const withLess = require('@zeit/next-less')
module.exports = withLess({
cssModules: true
})Create a Less file styles.less
@font-size: 50px;
.example {
font-size: @font-size;
}Create a page file pages/index.js
import css from "../styles.less"
export default () => <div className={css.example}>Hello World!</div>With CSS modules and options
You can also pass a list of options to the css-loader by passing an object called cssLoaderOptions.
For instance, to enable locally scoped CSS modules, you can write:
// next.config.js
const withLess = require('@zeit/next-less')
module.exports = withLess({
cssModules: true,
cssLoaderOptions: {
importLoaders: 1,
localIdentName: "[local]___[hash:base64:5]",
}
})Create a CSS file styles.css
.example {
font-size: 50px;
}Create a page file pages/index.js that imports your stylesheet and uses the hashed class name from the stylesheet
import css from "../style.css"
const Component = props => {
return (
<div className={css.backdrop}>
...
</div>
)
}
export default ComponentYour exported HTML will then reflect locally scoped CSS class names.
For a list of supported options, refer to the webpack css-loader README.
// ./pages/_document.js
import Document, { Head, Main, NextScript } from 'next/document'
export default class MyDocument extends Document {
render() {
return (
<html>
<Head>
<link rel="stylesheet" href="/_next/static/style.css" />
</Head>
<body>
<Main />
<NextScript />
</body>
</html>
)
}
}PostCSS plugins
Create a next.config.js in your project
// next.config.js
const withLess = require('@zeit/next-less')
module.exports = withLess()Create a postcss.config.js
module.exports = {
plugins: {
// Illustrational
'postcss-css-variables': {}
}
}Create a CSS file styles.scss the CSS here is using the css-variables postcss plugin.
:root {
--some-color: red;
}
.example {
/* red */
color: var(--some-color);
}When postcss.config.js is not found postcss-loader will not be added and will not cause overhead.
You can also pass a list of options to the postcss-loader by passing an object called postcssLoaderOptions.
For example, to pass theme env variables to postcss-loader, you can write:
// next.config.js
const withLess = require('@zeit/next-less')
module.exports = withLess({
postcssLoaderOptions: {
parser: true,
config: {
ctx: {
theme: JSON.stringify(process.env.REACT_APP_THEME)
}
}
}
})Configuring Next.js
Optionally you can add your custom Next.js configuration as parameter
// next.config.js
const withLess = require('@zeit/next-less')
module.exports = withLess({
webpack(config, options) {
return config
}
})