npm build.js

const path = require('path');
const fs = require('fs');

const vendor_dir = path.resolve(__dirname, 'public/static/vendor')

function copyFromNodeModules(src, dest) {
    /*
     * src - relative from node_modules directory
     * dest - should be absolute path
     */
    for (let dir in module.paths) {
        let file = path.resolve(module.paths[dir], src);
        if (fs.existsSync(file)) {
            fs.mkdirSync(path.dirname(dest), {recursive: true});
            fs.copyFile(file, dest, (err) => {
                if (err) {
                    throw err;
                }
                console.log(`Copy file: "${file}" to: "${dest}"`);
            });
            return true
        }
    }
    throw new Error(`File: "${src}" not found in paths: ${module.paths}`)
}

// Cleanup
fs.rmSync(vendor_dir, {recursive: true, force: true});
fs.mkdirSync(vendor_dir, {recursive: true});

// Copy files
copyFromNodeModules('bootstrap/dist/js/bootstrap.bundle.min.js', path.resolve(vendor_dir, 'bootstrap/bootstrap.bundle.min.js'));
copyFromNodeModules('bootstrap/dist/css/bootstrap.min.css', path.resolve(vendor_dir, 'bootstrap/bootstrap.min.css'));
copyFromNodeModules('bootstrap/dist/css/bootstrap.min.css.map', path.resolve(vendor_dir, 'bootstrap/bootstrap.min.css.map'));