Find duplicate dependencies in Node.js project

dup.js

  $("dup", async () => {
    if (fs.existsSync("pnpm-lock.yaml")) {
      const { packages } = yaml.load(fs.readFileSync("pnpm-lock.yaml", "utf8"));
      let last = ["", ""];
      let seen = new Set();
      const log = (s) => seen.has(s) || (seen.add(s), console.log(s));
      for (const path in packages) {
        const i = path.lastIndexOf("@");
        const pkg = path.slice(1, i);
        const ver = path.slice(i + 1);
        if (last[0] == pkg) {
          log(last.join("@"));
          log(pkg + "@" + ver);
        }
        last = [pkg, ver];
      }
      return;
    }
    console.log("don't know how to handle this project");
  });