$(this) vs this

// jQuery
$('#buttongroup1 button').click(function (e) {
    const val = $(this).text(); // or $(e.target).text();
    $('pre:first-of-type').html(`You clicked on <b>${val}</b>`);
});

// vanilla JS
document.querySelectorAll('#buttongroup2 button').forEach(function (button) {
    button.addEventListener('click', function (e) {
        const val = this.textContent; // or e.target.textContent
        document.querySelector('pre:first-of-type').innerHTML = `You clicked on <b>${val}</b>`;
    });
});