A Deno script that fetches the mostly commonly used folder names in popular NPM packages. Read the blog post: https://www.elidrissi.dev/posts/2023/02/most-used-folder-names-npm-packages/

most_used_folder_names_npm_packages.js

import packages from "./packages.json" assert { type: "json" };

const NPM_REGISTRY_API_URL = "https://registry.npmjs.com";
const GITHUB_API_URL = "https://api.github.com";

const fallbackRepoURL = {
  yarn: 'https://github.com/yarnpkg/yarn'
};
const directories = new Map();

console.log('Fetching packages information...');
const pkgs = await Promise.all(
  packages.map(name =>
    fetch(`${NPM_REGISTRY_API_URL}/${name}`)
      .then(res => res.json())
      .catch(console.error)
  )
);

console.log('Fetching repositories information...');
const repos = await Promise.all(
  pkgs.map(pkg => {
    // Parse the repo URL for every package, fallback to a predefined
    // map when a URL is unavailable
    const githubUrl = new URL(pkg.repository.url ?? fallbackRepoURL[pkg.name]);
    const repoNamespace = githubUrl.pathname.replace(/\.git$/i, "");

    return fetch(`${GITHUB_API_URL}/repos${repoNamespace}/contents`)
      .then(res => res.json())
      .catch(console.error);
  })
);

repos.flat()
  .filter(file => file.type === 'dir')
  .map(dir => dir.name)
  .forEach(dir => {
    let count = directories.get(dir);
    directories.set(dir, count ? ++count : 1);
  });

const dirs = Array.from(directories.entries())
  // Filter out the directories that appear only once
  .filter(v => v[1] > 1)
  // Sort desc by their count
  .sort((a, b) => b[1] - a[1]);

// Print out the result
for (let [dir, count] of dirs) {
  console.log(dir, ':', count);
}

packages.json

[
  "acorn",
  "async",
  "axios",
  "@babel/cli",
  "bluebird",
  "bootstrap",
  "chalk",
  "classnames",
  "colors",
  "commander",
  "core-js",
  "cors",
  "d3",
  "debug",
  "dotenv",
  "ejs",
  "enzyme",
  "escape-html",
  "eslint",
  "express",
  "formik",
  "fs-extra",
  "glob",
  "graphql",
  "gulp",
  "helmet",
  "history",
  "husky",
  "i18next",
  "ioredis",
  "jest",
  "jquery",
  "jsonwebtoken",
  "jws",
  "karma",
  "koa",
  "lodash",
  "mkdirp",
  "mocha",
  "moment",
  "mongodb",
  "msw",
  "nanoid",
  "next",
  "node-fetch",
  "passport",
  "postcss",
  "prisma",
  "prop-types",
  "react-dom",
  "react-hook-form",
  "react",
  "redux",
  "request",
  "rxjs",
  "sass",
  "styled-components",
  "swr",
  "tailwindcss",
  "tslib",
  "underscore",
  "uuid",
  "vite",
  "vue",
  "webpack",
  "winston",
  "yaml",
  "yarn",
  "yargs",
  "zod"
]