install-pkg-lock/lib/main.js

Only npm install if package-lock.json has been modified

const fs = require("fs");
const path = require("path");
const crypto = require("crypto");
const execSync = require("child_process").execSync;

// hashes a given file and returns the hex digest
const hashFile = (filepath) => {
  const hashSum = crypto.createHash("md5");
  const contents = fs.readFileSync(filepath, "utf-8");

  hashSum.update(Buffer.from(contents));
  return hashSum.digest("hex");
};

const findPackageJson = (lockFilename) => {
  let current = process.cwd();
  let last = current;
  do {
    const search = path.join(current, lockFilename);
    if (fs.existsSync(search)) {
      return search;
    }
    last = current;
    current = path.dirname(current);
  } while (current !== last);
};

// returns whether or not npm install should be executed
const watchFile = ({
  hashFilename = "packagehash.txt",
  lockFilename = "package-lock.json",
  installCommand = "npm install",
  isHashOnly = false,
}) => {
  const packagePath = findPackageJson(lockFilename);

  if (!packagePath) {
    console.error(
      `Cannot find ${lockFilename}. Travelling up from current working directory`
    );
  }

  const packageHashPath = path.join(path.dirname(packagePath), hashFilename);
  const recentDigest = hashFile(packagePath);

  // if the hash file doesn't exist
  // or if it does and the hash is different
  if (
    !fs.existsSync(packageHashPath) ||
    fs.readFileSync(packageHashPath, "utf-8") !== recentDigest
  ) {
    console.log(`${lockFilename} has been modified.`);

    if (isHashOnly) {
      console.log("Updating hash only because --hash-only is true.");

      fs.writeFileSync(packageHashPath, recentDigest); // write to hash to file for future use
      return true;
    }

    console.log("Installing and updating hash.");

    try {
      execSync(installCommand, {
        stdio: "inherit",
      });
      fs.writeFileSync(packageHashPath, recentDigest); // write to hash to file for future use
    } catch (error) {
      console.log(error);
    }
    return true;
  }
  console.log(`${lockFilename} has not been modified.`);
  return false;
};

module.exports = watchFile;