topPackageAuthors.js

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

const modules = fs.readdirSync('node_modules');
const pkgAndAuthor = modules
    .map(m => path.join(__dirname, 'node_modules', m, 'package.json'))
    .filter(pkg => fs.existsSync(pkg))
    .map(pkg => require(pkg))
    .map(p => ({author: p.author, pkgName: p.name}))
    .filter(d => d.author)
    .map(d => ({author: d.author.name ? d.author.name : d.author, pkgName: d.pkgName}))
  ;

const total = pkgAndAuthor.length;
const groupedByAuthor = groupBy(pkgAndAuthor, 'author');
const howMany = mapObject(groupedByAuthor, modules => modules.length);

const table = [];
Object.keys(howMany).forEach(author => {
  const count = howMany[author];
  table.push({author, count})
});

table
  .sort((d1, d2) => d2.count - d1.count);

const percents = table.map(r => {
  const percent = ((r.count / total) * 100).toFixed(2);
  return {
    author: r.author,
    modules: `${r.count}/${total} (${percent}%)`
  }
});
console.log(tablify(percents));


function mapObject(obj, fn) {
  return Object.keys(obj).reduce(
    (res, key) => {
      res[key] = fn(obj[key]);
      return res;
    },
    {}
  )
}

function groupBy(collection, attribute) {
  return collection.reduce(
    (res, item) => {
      const value = item[attribute];
      if (!res[value]) {
        res[value] = [];
      }
      res[value].push(item);
      return res;
    },
    {}
  )
}