A middleware for automatically remove temporary multer middleware files after the response is close

middleware_multer_del.ts

import { unlinkSync } from "node:fs"
import { Request, Response, NextFunction } from "express"

async function temporaryFileRemoverMiddleware(
    req: Request,
    res: Response,
    next: NextFunction,
  ) {
    async function asyncUnlink(path: string) {
      unlinkSync(path);
    }

    // After res is closed
    res.on('close', () => {
      // Removing on req.file
      if (typeof req.file != 'undefined') {
        let file = req.file;
        asyncUnlink(file.path).catch(() =>
          log.error(`Failed to remove ${file.path}`),
        );
      }

      // Removing req.files
      const files = req.files;
      if (typeof files != 'undefined') {
        // On Express.Multer.File[]
        if (Array.isArray(files)) {
          files.forEach((file) => {
            asyncUnlink(file.path).catch(() =>
              console.log(`Failed to remove ${file.path}`),
            );
          });
        } else {
          // On { [fieldname: string]: Express.Multer.File[] }
          let keys = Object.keys(files);
          keys.forEach((key) => {
            let keyFiles = files[key];
            if (Array.isArray(keyFiles)) {
              keyFiles.forEach((file) => {
                asyncUnlink(file.path).catch(() =>
                  console.log(`Failed to remove ${file.path}`),
                );
              });
            }
          });
        }
      }
    });

    next();
  }