minify-client.js

import fs from "fs";
import path from "path";
import walk from "walk";
import terser from "terser";

const CLIENT_FILES_PATH = "./resources/main/client";
const OUTPUT_DIR = "client_minified";

let walker = walk.walk(CLIENT_FILES_PATH, { followLinks: false });
let files = [];

walker.on("file", (root, stat, next) => {
    files.push(root + "/" + stat.name);
    next();
});

walker.on("end", () => {
    files.forEach(async (file) => {
        try {
            let source = await fs.promises.readFile(file);
            let minified = terser.minify(source.toString(), {
                ecma: 8,
                keep_classnames: true,
                keep_fnames: true,
                mangle: false,
                compress: {
                    ecma: 8,
                },
            });
            if (minified.error)
                return console.error(
                    `Error while minifying '${file}': ${minified.error.stack}`
                );
            let output = file.replace("client", OUTPUT_DIR);
            let dirs = path.join(output, "..");
            await fs.promises.mkdir(dirs, { recursive: true });
            await fs.promises.writeFile(output, minified.code);
            console.log(`Minfied '${file}'`);
        } catch (e) {
            console.error(`Error while writing '${file}': ${e.stack}`);
        }
    });
});