Node Multer unexpected field

This for the Api you could use

 const express        = require('express');
 const bodyParser     = require('body-parser');
 const app = express();
 var multer = require('multer');
 const port = 8000;
 app.use(bodyParser.json());
 app.use(bodyParser.urlencoded({ extended: true }));

 app.listen(port, ()=>{
 console.log('We are live on' + port);
 });

 var upload = multer({dest:'./upload/'});

 app.post('/post', upload.single('file'), function(req, res) {
  console.log(req.file);
 res.send("file saved on server");
 });

This also works fine used on Postman but the file doesn't comes with .jpg extension any Advice? As commented below

This is the default feature of multer if uploads file with no extension, however, provides you the the file object, using which you can update the extension of the file.

var filename = req.file.filename; 
var mimetype = req.file.mimetype; 
mimetype = mimetype.split("/"); 
var filetype = mimetype[1]; 
var old_file = configUploading.settings.rootPathTmp+filename; 
var new_file = configUploading.settings.rootPathTmp+filename+'.'+filetype; 
rname(old_file,new_file);

A follow up to vincent's answer.

Not a direct answer to the question since the question is using a form.

For me, it wasn't the name of the input tag that was used, but the name when appending the file to the formData.

front end file

   var formData = new FormData();
   formData.append('<NAME>',this.new_attachments)

web service file:

   app.post('/upload', upload.single('<NAME>'),...

The <NAME> you use in multer's upload.single(<NAME>) function must be the same as the one you use in <input type="file" name="<NAME>" ...>.

So you need to change

var type = upload.single('file')

to

var type = upload.single('recfile')

in you app.js

We have to make sure the type= file with name attribute should be same as the parameter name passed in upload.single('attr')

var multer  = require('multer');
var upload = multer({ dest: 'upload/'});
var fs = require('fs');

/** Permissible loading a single file, 
    the value of the attribute "name" in the form of "recfile". **/
var type = upload.single('recfile');

app.post('/upload', type, function (req,res) {

  /** When using the "single"
      data come in "req.file" regardless of the attribute "name". **/
  var tmp_path = req.file.path;

  /** The original name of the uploaded file
      stored in the variable "originalname". **/
  var target_path = 'uploads/' + req.file.originalname;

  /** A better way to copy the uploaded file. **/
  var src = fs.createReadStream(tmp_path);
  var dest = fs.createWriteStream(target_path);
  src.pipe(dest);
  src.on('end', function() { res.render('complete'); });
  src.on('error', function(err) { res.render('error'); });

});