rollup.config.js

// rollup.config.js
import peerDepsExternal from 'rollup-plugin-peer-deps-external';
import resolve from '@rollup/plugin-node-resolve';
import commonjs from '@rollup/plugin-commonjs';
import typescript from 'rollup-plugin-typescript2';
import postcss from 'rollup-plugin-postcss';
import json from '@rollup/plugin-json';
const { babel } = require('@rollup/plugin-babel');
const packageJson = require('./package.json');
const less = require('less');

const isProd = process.env.NODE_ENV === 'production';

const babelOptions = {
  presets: ['@babel/preset-env'],
  extensions: ['.js', '.jsx', '.ts', '.tsx', '.less'],
  exclude: '**/node_modules/**',
};

const processLess = function (context, payload) {
  return new Promise((resolve, reject) => {
    less.render(
      {
        file: context,
      },
      function (err, result) {
        if (!err) {
          resolve(result);
        } else {
          reject(err);
        }
      },
    );
    less.render(context, {}).then(
      function (output) {
        if (output && output.css) {
          resolve(output.css);
        } else {
          reject({});
        }
      },
      function (err) {
        reject(err);
      },
    );
  });
};

export default {
  input: 'packages/index.ts',
  output: [
    {
      file: packageJson.main,
      format: 'cjs',
    },
    {
      file: packageJson.module,
      format: 'es',
    },
  ],
  plugins: [
    peerDepsExternal({ includeDependencies: !isProd }),
    resolve(),
    commonjs({ sourceMap: !isProd }),
    typescript({ useTsconfigDeclarationDir: true }),
    postcss({
      extract: true,
      process: processLess,
    }),
    babel(babelOptions),
    json(),
  ],
};