logger.js

const { createLogger, format, transports } = require('winston');

class Logger {
  constructor() {
    this.logger = createLogger({
      transports: new transports.File({
        level: 'error',
        filename: 'error.log',
        format: format.json(),
        ``
      }),
    });
  }

  logError(err) {
    this.logger.error(err);
  }
}

module.exports = Logger;

As you can see I am using prototype method.So that I don't have to use new method to create object. I have attached all the 3 files. Just want to know how can I use logger in user.js file without using new keyword in logger.js file.

user.js

exports.postUser = async (req, res, next) => {

      try {

        console.log(`name:${JSON.stringify(req.body)}`)

        throw new Error('this is an error on the post');

        let user = new User({
          name: req.body.name,
          age: parseInt(req.body.age),
          city: req.body.city,
          status: 'ACTIVE'
        })

        let savedPost = await user.save();
        console.log(`savedPost':${JSON.stringify(savedPost)}`);
        res.json(savedPost);
      } catch (err) {

        console.log(`err:${err.toString()}`)
        res.status(500).json({ message: err })
   

here I want to call the logger .So that it can return method, err, date.

logger.prototype.logError = function() {
  return (`function:controller.postUser, error:${err.toString()} -method: ${req.method}- body:${JSON.stringify(req.body)}  date:${new Date(Date.now()).toUTCString()}`)
}
};

routes.js

const router = require('express').Router();
const { json } = require('body-parser');
const User = require('../models/user');
const controller = require('../controllers/user');
const middle = require('../middleware/middleware')

/*routes*/
router.get('/', controller.getUser);

router.post('/', middle.verify, controller.postUser);

router.put('/:userId', controller.updateUser)

router.delete('/:userId', controller.deleteUser);

module.exports = router