Ajax call in react js

Hi I am new to react js.I am trying to make a ajax call in react js to get data
This is my code for ajax call

$.ajax({
type: 'POST',
url: '/menu-item',
data: checkBox
})
.done(function (data) {
alert(data);
})
.fail(function (data) {
console.log('failed to register');
});

Here I am getting an error as:

POST http://localhost:3000/menu-item 404 (Not Found)

I don't know which method I have to pass theurl.
This my .js file

var express = require('express');
//express.use(require('connect').bodyParser());
var router = express();
var path = require('path');
var Menu = require('../models/menu');
var bCrypt = require('bcrypt-nodejs');
var db = require('../db');
var mongoose = require('mongoose');

module.exports = function(passport) {
        router.post('/menu-item', function(req, res) {

console.log("------request-------"+req);

  var formDetails = {

        checkBox: req.body.checkBox
  };
  
  var newFormDetails = new Menu({
        checkBox: formDetails.checkBox
        
  });
  newFormDetails.save(function(saveErr, formId) {
    if (saveErr){
      res.notFound();
    } else {
      res.send(newFormDetails);
      console.log("Saved successfully"+newFormDetails);
    };
  });
});

return router;

}

Please any suggestion..

via Lynda Noel