@runforest/js/rollup-minify/index.js

const {minify} = require('terser');

const terserOptions = {
    sourceMap: true,
    mangle: {
        // Pass true to work around the Safari 10 loop iterator bug "Cannot
        // declare a let variable twice".
        // https://bugs.webkit.org/show_bug.cgi?id=171041
        safari10: true,
    },
    // Set this option to true to work around the Safari 10/11 await bug.
    // https://bugs.webkit.org/show_bug.cgi?id=176685
    output: {
        safari10: true,
    },
};

/**
 * Chunk transformer function called for each Rollup output chunk file.
 * @param {string} source Source code.
 * @return {Object}
 */
const transformChunk = function(source) {
    const result = minify(source, terserOptions);

    if (result.error) {
        throw result.error;
    }

    return result;
};

module.exports = function() {
    return {
        name: 'minify',
        transformChunk: transformChunk,
    };
};