react-native-sass-transformer   

Use Sass to style your React Native apps.

Behind the scenes the Sass files are transformed to react native style objects (look at the examples).

> This transformer can be used together with React Native CSS modules.

How does it work?

Your App.scss file might look like this:

``scss
%blue {
color: blue;
}
.myClass {
@extend %blue;
}
.myOtherClass {
color: red;
}
.my-dashed-class {
color: green;
}
`

When you import your stylesheet:

`js
import styles from "./App.scss";
`

Your imported styles will look like this:

`js
var styles = {
myClass: {
color: "blue"
},
myOtherClass: {
color: "red"
},
"my-dashed-class": {
color: "green"
}
};
`

You can then use that style object with an element:

Plain React Native:

`jsx



`

React Native CSS modules using className property:

`jsx



`

React Native CSS modules using styleName property:

`jsx

`

_Please use the .scss file extension for SCSS syntax and the .sass file extension for indented Sass syntax._

Installation and configuration

$3

`sh
yarn add --dev react-native-sass-transformer sass
`

$3

#### For Expo SDK v41.0.0 or newer

Merge the contents from your project's metro.config.js file with this config (create the file if it does not exist already).

metro.config.js:

`js
const { getDefaultConfig } = require("expo/metro-config");

module.exports = (() => {
const config = getDefaultConfig(__dirname);

const { transformer, resolver } = config;

config.transformer = {
...transformer,
babelTransformerPath: require.resolve("react-native-sass-transformer")
};
config.resolver = {
...resolver,
sourceExts: [...sourceExts, "scss", "sass"]
};

return config;
})();
`

---

#### For React Native v0.72.1 or newer

Merge the contents from your project's metro.config.js file with this config (create the file if it does not exist already).

metro.config.js:

`js
const { getDefaultConfig, mergeConfig } = require("@react-native/metro-config");

const defaultConfig = getDefaultConfig(__dirname);
const { assetExts, sourceExts } = defaultConfig.resolver;

/**
* Metro configuration
* https://reactnative.dev/docs/metro
*
* @type {import('metro-config').MetroConfig}
*/
const config = {
transformer: {
babelTransformerPath: require.resolve("react-native-sass-transformer")
},
resolver: {
sourceExts: [...sourceExts, "scss", "sass"]
}
};

module.exports = mergeConfig(defaultConfig, config);
`

Platform specific extensions

If you need React Native's platform specific extensions for your Sass files, you can use babel-plugin-react-native-platform-specific-extensions. Platform specific extensions for files imported using Sass' @import are supported by default.

Sass options

If you need to pass options (e.g. functions) to sass, you can do so by creating a transformer.js file and doing the following:

`js
const upstreamTransformer = require("@react-native/metro-babel-transformer");
const sassTransformer = require("react-native-sass-transformer");

module.exports.transform = function ({ src, filename, options, ...rest }) {
if (filename.endsWith(".scss") || filename.endsWith(".sass")) {
const opts = Object.assign(options, {
sassOptions: {
functions: {
"rem($px)": (px) => {
px.setValue(px.getValue() / 16);
px.setUnit("rem");
return px;
}
}
}
});
return sassTransformer.transform({ src, filename, options: opts, ...rest });
} else {
return upstreamTransformer.transform({ src, filename, options, ...rest });
}
};
`

After that in metro.config.js point the babelTransformerPath to that file:

`js
const { getDefaultConfig, mergeConfig } = require("@react-native/metro-config");

const defaultConfig = getDefaultConfig(__dirname);
const { assetExts, sourceExts } = defaultConfig.resolver;

/**
* Metro configuration
* https://reactnative.dev/docs/metro
*
* @type {import('metro-config').MetroConfig}
*/
const config = {
transformer: {
babelTransformerPath: require.resolve("./transformer.js")
},
resolver: {
sourceExts: [...sourceExts, "scss", "sass"]
}
};

module.exports = mergeConfig(defaultConfig, config);
`

CSS Custom Properties (CSS variables)

_You need version 1.4.0 or newer_

`css
:root {
--text-color: blue;
}

.blue {
color: var(--text-color);
}
`

CSS variables are not supported by default, but you can add support for them by using PostCSS and postcss-css-variables plugin.

Start by installing dependencies:

`sh
yarn add postcss postcss-css-variables react-native-postcss-transformer --dev
`

Add postcss-css-variables to your PostCSS configuration with one of the supported config formats, e.g. package.json, .postcssrc, postcss.config.js, etc.

After that create a transformer.js file and do the following:

`js
const upstreamTransformer = require("@react-native/metro-babel-transformer");
const sassTransformer = require("react-native-sass-transformer");
const postCSSTransformer = require("react-native-postcss-transformer");

module.exports.transform = function ({ src, filename, ...rest }) {
if (filename.endsWith(".scss") || filename.endsWith(".sass")) {
return sassTransformer
.renderToCSS({ src, filename, options })
.then((css) =>
postCSSTransformer.transform({ src: css, filename, ...rest })
);
} else {
return upstreamTransformer.transform({ src, filename, ...rest });
}
};
`

After that in metro.config.js point the babelTransformerPath to that file:

`js
const { getDefaultConfig, mergeConfig } = require("@react-native/metro-config");

const defaultConfig = getDefaultConfig(__dirname);
const { assetExts, sourceExts } = defaultConfig.resolver;

/**
* Metro configuration
* https://reactnative.dev/docs/metro
*
* @type {import('metro-config').MetroConfig}
*/
const config = {
transformer: {
babelTransformerPath: require.resolve("./transformer.js")
},
resolver: {
sourceExts: [...sourceExts, "scss", "sass"]
}
};

module.exports = mergeConfig(defaultConfig, config);
``

Dependencies

This library has the following Node.js modules as dependencies:

- app-root-path
- css-to-react-native-transform