I am trying to use ajax to send data from client-side to server-side without refreshing the page.

I am using this ajax code inside my pug file -

script.
        $(function() {
            $('#form1').submit(function(event) {
                event.preventDefault();
                var form = $(this);
                $.ajax({
                    type: form.attr('method'),
                    url: form.attr('action'),
                    data: {form.serialize()}
                });
            });
        });

I am using the same URL and the method(which is POST).

Router file:-

const express = require("express");

const main_controller = require("../../controllers/main-controller");

const router = express.Router();

router.post('/form', main_controller.Send);

module.exports = router;

Controller file:-

const data_model = require('../../models/data-model');

exports.Send = (req, res, next) => {
    data_model.find((err, data) => {
        res.render("./customer/form1", {
            pageTitle: "Form1",
            data: data
        });
    });
};

I want to filter the data I am sending above. In the form, I have dropdown boxes in which I'm displaying the data, when the user selects something, I am sending the option he chose to the server. In the server, I am filtering data based on the option that was selected. I want to send the filtered data back to the client-side, but I am not able to.