Package up Vue components & exports into index.js (no deps, tested Node 18 LTS)

build-indexes.js

import { readdir, readFile, writeFile } from 'node:fs/promises';

const parseDir = async (path, directoriesOnly) => {
  return (await readdir(path, {withFileTypes: true}))
    .filter(file => file.isDirectory() == directoriesOnly)
    .map(file => file.name);
}

const determineImportExports = async ({dir, file}) => {
  if ( file.endsWith('.vue') )
  {
    const componentName = file.substring(0, file.lastIndexOf('.'))
    return {file, components: [componentName]};
  }

  const contents = await readFile(`./${dir}/${file}`, {encoding: 'utf-8'});
  const m = new RegExp("export {([^}]+)}").exec(contents);
  if ( ! m ) {
    return false;
  }
  
  return {file, components: m[1].split(',').map(s => s.trim())}
};

const generateImports = ({file, components}) => {
  if (!components?.length) {
    return '';
  }
  if ( file.endsWith('.vue') ) {
    return `import ${components[0]} from './${file}'`
  }

  return `import { ${components.join(', ')} } from './${file}'`
};

const generateExports = ({components}) => {
  return components.map(c => `  ${c}`).join(",\n")
};

const dirs = await parseDir('./', true);

const fileTypes = ['.vue', '.ts', '.js'];

const ignoredFiles = ['index.ts', 'index.js'];

dirs.forEach(async dir => {
  let files = (await parseDir(`./${dir}`, false))
    .filter(file => !ignoredFiles.some(ignored => file === ignored))
    .filter(file => fileTypes.some(type => file.endsWith(type)))
    .map(file => ({dir, file}));

  if ( files.length === 0 ) {
    return;
  }
  
  let importExports = (await Promise.all(files.map(determineImportExports))).filter(({components}) => components?.length)

  if ( importExports.length === 0 ) {
    return;
  }
  const count = importExports.reduce((p, {components}) => p + components.length, 0)
  const header = `// build-index of ./${dir} (${count})`
  const imports = importExports.map(generateImports).join("\n");
  const exports = importExports.map(generateExports).join(",\n");

  const output = [header, imports, '', 'export {', exports, '}', ''].join("\n");
  await writeFile(`./${dir}/index.js`, output);
})