Is there a way to access DOM serverside?

I am trying to break free from tutorial hell and create something to make my life easier (the irony), it's an hours calculator.

I won't go too much into the functionality but basically it's just an app that stores all my months hours to which I can calculate at the end of the month by clicking a button.

However I am stuck, I am fairly new to this (backend especially) and I can't find a way to access the DOM and from my understanding that's normal given it's serverside code.

However I just need to know how you grab DOM elements and assign them to variables if this functionality doesn't exist backend? Is there an alternative to...

document.querySelector('...')

?

I did install JSDOM however from my understanding you can only pass in sections of code as opposed to accessing the full page? I may be completely wrong...

Can someone please help me get a clearer understanding of what I need to understand/do?

Here is my app.js code, go easy :)

const express = require('express'),
    app = express(),
    bodyParser = require('body-parser'),
    mongoose = require('mongoose'),
    jsdom = require("jsdom"),
    { JSDOM } = jsdom,
    dom = new JSDOM('localhost:3000/');

// ----------------------------------------//
const date = new Date(),
    day = date.getDate(),
    month = date.toLocaleString('default', { month: 'long' }),
    table = dom.window.document.querySelector('table'),
    totalShiftHours = dom.window.document.querySelectorAll('.totalShiftHours');



app.use(bodyParser.urlencoded({ extended: true }));
app.use(express.static('public'));
app.set('view engine', 'ejs');
app.listen(3000, () => console.log("I'm listening"));
mongoose.connect('mongodb://localhost:27017/hours_calculator', { useNewUrlParser: true, useUnifiedTopology: true });

const shiftSchema = new mongoose.Schema({
    date: Number,
    startTime: Number,
    finishTime: Number,
    lunchTime: Number,
});
const Shift = mongoose.model('Shift', shiftSchema);

app.get('/', (req, res) => {
    Shift.find({}, (err, allShifts) => {
        if (err) console.log(`There's an error: ${err}`)
        else res.render('index', {
            shifts: allShifts,
            day: day,
            month: month,
            table: table,
            totalShiftHours: totalShiftHours
        })
    })
});

app.post('/', (req, res) => {
    const startTime = Number(req.body.startTime),
        finishTime = Number(req.body.endTime),
        lunchTime = Number(req.body.lunchTime),
        newShift = {
            date: day,
            startTime: startTime,
            finishTime: finishTime,
            lunchTime: lunchTime
        };
    Shift.create(newShift, (err, newShift) => {
        if (err) console.log(`Somethings wrong, ${err}`);
        else res.redirect('/')
    })
});