Count package versions across a JS monorepo

a_usage.sh

fd '**/package.json' | node count_versions_in_monorepo.js

count_versions_in_monorepo.js

const { strict: assert } = require('assert');
const fs = require('fs');
const readline = require('readline');

const depFields = ['dependencies', 'devDependencies', 'peerDependencies'];

function getAllDepVersions(pkgJsonObj) {
  const allDepVersions = [];
}

async function main() {
  const lines = await readLinesFromStdin();
  const pkgVersions = new Map();
  for (const line of lines) {
    assert(
      line.endsWith('package.json'),
      `expected a path to a package.json file, got ${line}`,
    );

    const pkgJsonObj = maybeReadJson(line);
    if (pkgJsonObj == null) {
      console.error(`skipping ${line}`);
      continue;
    }

    for (const depField of depFields) {
      if (!(depField in pkgJsonObj)) continue;
      for (const [name, version] of Object.entries(pkgJsonObj[depField])) {
        if (isLocalDependency(version)) continue;
        pushToKey(pkgVersions, name, version);
      }
    }
  }

  for (const [name, versions] of pkgVersions) {
    const uniqVersions = unique(versions);
    if (uniqVersions.length === 1) continue;
    console.log(`${name}: ${uniqVersions.sort().join(', ')}`);
  }
}

function isLocalDependency(version) {
  return (
    version.startsWith('file:')
    || version.startsWith('./')
    || version.startsWith('../')
  );
}

function unique(values) {
  return [...new Set(values)];
}

function pushToKey(map, key, value) {
  let arr = map.get(key);
  if (arr == null) {
    arr = [];
    map.set(key, arr);
  }
  arr.push(value);
}

function maybeReadJson(filepath) {
  try {
    return JSON.parse(fs.readFileSync(filepath, 'utf-8'));
  } catch (err) {
    return undefined;
  }
}

function readLinesFromStdin() {
  return new Promise((resolve, reject) => {
    const lines = [];
    const linereader = readline.createInterface({
      input: process.stdin,
      terminal: false,
    });
    linereader.on("line", (line) => lines.push(line));
    linereader.on("close", () => resolve(lines));
  });
}

main();