Search all packages that doesn't support ESM from node_modules directory

index.mjs

import * as path from 'node:path';
import * as fs from 'node:fs/promises';

const nodeModules = path.resolve('node_modules');

let moduleNames = await fs.readdir(nodeModules);
moduleNames = (await Promise.all(
  moduleNames.map(async name => {
    if (name.startsWith('.')) {
      return [];
    } else if (name.startsWith('@')) {
      const packages = await fs.readdir(path.join(nodeModules, name));
      return packages.map(pkg => `${name}/${pkg}`);
    } else {
      return name;
    }
  }),
)).flat();

const cjsModuleNames = (await Promise.all(
  moduleNames.map(async moduleName => {
    const content = await fs.readFile(path.join(nodeModules, moduleName, 'package.json'));
    const manifest = JSON.parse(content);
    function anyEntry(exports) {
      if (exports && typeof exports === 'object') {
        if (exports['import']) {
          return true;
        } else {
          for (const entry of Object.values(exports)) {
            return anyEntry(entry);
          }
        }
      }
      return false;
    }
    const predicate = (
      manifest['main']?.endsWith('.mjs') ||
      manifest['type'] === 'module' ||
      anyEntry(manifest['exports'])
    );
    return predicate ? null : moduleName;
  }),
)).filter(Boolean);

console.log(cjsModuleNames);