listing.js

let $ = require('jquery');
let fs = require('fs');
let filename = 'contacts';
let sno = 0;

$('#add-to-list').on('click', () => {
    let name = $('#Name').val();
    let email = $('#Email').val();

    fs.appendFile('contacts', name + ',' + email + '\n');

    addEntry(name, email);
});

function addEntry(name, email) {
    if (name && email) {
        sno++;
        let updateString = '<tr><td>' + sno + '</td><td>' + name + '</td><td>' +
            email + '</td></tr>';
        $('#contact-table').append(updateString);
    }
};

function loadAndDisplayContacts() {

    //Check if file exists
    if (fs.existsSync(filename)) {
        let data = fs.readFileSync(filename, 'utf8').split('\n');

        data.forEach((contact, index) => {
            let [name, email] = contact.split(',');
            addEntry(name, email);
        });

    } else {
        console.log("File Doesn\'t Exist. Creating new file.");
        fs.writeFile(filename, '', (err) => {
            if (err)
                console.log(err);
        })
    }
}

loadAndDisplayContacts();