react-native-typed-less-transformer

    0.11.1 • Public • Published

    react-native-typed-less-transformer

    NPM version Downloads per month contributions welcome

    Load Less files to react native style objects.

    This transformer also generates .d.ts Typescript typings for the Less files. Notice that platform specific extensions are not supported in the Typescript typings.

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

    Minimum React Native version for this transformer is 0.52. If you are using an older version, please update to a newer React Native version before trying to use this transformer.

    Usage

    Step 1: Install

    yarn add --dev react-native-typed-less-transformer less

    Step 2: Configure the react native packager

    For React Native v0.57 or newer / Expo SDK v31.0.0 or newer

    Add this to metro.config.js in your project's root (create the file if it does not exist already):

    const { getDefaultConfig } = require("metro-config");
    module.exports = (async () => {
      const {
        resolver: { sourceExts } 
      } = await getDefaultConfig();
      return {
        transformer: {
          babelTransformerPath: require.resolve(
            "react-native-typed-less-transformer"
          )
        },
        resolver: {
          sourceExts: [...sourceExts, "less"]
        }
      };
    })();

    If you are using Expo, you also need to add this to app.json:

    {
      "expo": {
        "packagerOpts": {
          "config": "metro.config.js"
        }
      }
    }

    For React Native v0.56 or older

    If you are using React Native without Expo, add this to rn-cli.config.js in your project's root (create the file if you don't have one already):

    module.exports = {
      getTransformModulePath() {
        return require.resolve("react-native-typed-less-transformer");
      },
      getSourceExts() {
        return ["js", "jsx", "less"];
      }
    };

    For Expo SDK v30.0.0 or older

    If you are using Expo, instead of adding the rn-cli.config.js file, you need to add this to app.json:

    {
      "expo": {
        "packagerOpts": {
          "sourceExts": ["js", "jsx", "less"],
          "transformer": "node_modules/react-native-typed-less-transformer/index.js"
        }
      }
    }

    How does it work?

    Your App.less file might look like this:

    @nice-blue: #5b83ad;
    @light-blue: @nice-blue + #111;
     
    .myClass {
      color: @light-blue;
    }
    .myOtherClass {
      color: red;
    }

    When you import your stylesheet:

    import styles from "./App.less";

    Your imported styles will look like this:

    var styles = {
      myClass: {
        color: "#6c94be"
      },
      myOtherClass: {
        color: "red"
      }
    };

    The generated App.less.d.ts file looks like this:

    export const myClass: string;
    export const myOtherClass: string;

    You can then use that style object with an element:

    <MyElement style={styles.myClass} />

    CSS Custom Properties (CSS variables)

    You need version 0.11.1 or newer

    :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:

    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:

    // For React Native version 0.59 or later
    var upstreamTransformer = require("metro-react-native-babel-transformer");
     
    // For React Native version 0.56-0.58
    // var upstreamTransformer = require("metro/src/reactNativeTransformer");
     
    // For React Native version 0.52-0.55
    // var upstreamTransformer = require("metro/src/transformer");
     
    // For React Native version 0.47-0.51
    // var upstreamTransformer = require("metro-bundler/src/transformer");
     
    // For React Native version 0.46
    // var upstreamTransformer = require("metro-bundler/build/transformer");
     
    var lessTransformer = require("react-native-typed-less-transformer");
    var postCSSTransformer = require("react-native-postcss-transformer");
     
    module.exports.transform = function({ src, filename, options }) {
      if (filename.endsWith(".less")) {
        return lessTransformer
          .renderToCSS({ src, filename, options })
          .then(css =>
            postCSSTransformer.transform({ src: css, filename, options })
          );
      } else {
        return upstreamTransformer.transform({ src, filename, options });
      }
    };

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

    const { getDefaultConfig } = require("metro-config");
     
    module.exports = (async () => {
      const {
        resolver: { sourceExts } 
      } = await getDefaultConfig();
      return {
        transformer: {
          babelTransformerPath: require.resolve("./transformer.js")
        },
        resolver: {
          sourceExts: [...sourceExts, "less"]
        }
      };
    })();

    Keywords

    none

    Install

    npm i react-native-typed-less-transformer

    DownloadsWeekly Downloads

    6

    Version

    0.11.1

    License

    MIT

    Unpacked Size

    11.1 kB

    Total Files

    4

    Last publish

    Collaborators

    • kristerkari