Node binary to delete duplicate files in a directory

delete-duplicate-files.js

#!/usr/local/bin/node

/*
 * Usage: in-place deletion of duplicate files within a folder.
 * ```
 * ./deleteDuplicates.js relative/folder/path/of/duplicate/files
 * ```
 *
 * You may need to change the access control to run this as an executable.
 * ```
 * chmod 755 deleteDuplicates.js
 * ```
 *
 * Keep in mind this will delete *in place*, so make a backup of your folder
 * if you think you may need to keep the duplicates for whatever reason.
 *
 */

const crypto = require("crypto");
const fs = require("fs");

const folder = process.argv[2];
const absoluteFolder = `${__dirname}/${folder}`;

fs.readdir(absoluteFolder, (err, files) => {
  if (err) {
    console.log(err);
    return;
  }

  const map = {};

  files.forEach(filename => {
    const absoluteFilePath = `${absoluteFolder}/${filename}`;

    if (fs.existsSync(absoluteFilePath)) {
      const input = fs.createReadStream(absoluteFilePath);
      const hash = crypto.createHash("sha256");

      hash.setEncoding("hex");

      input.on("end", () => {
        hash.end();
        const hashValue = hash.read();

        if (map[hashValue]) {
          fs.unlinkSync(absoluteFilePath);
        } else {
          map[hashValue] = true;
        }
      });

      input.pipe(hash);
    }
  });
});