[рони]

Dolf,
пробуйте

$(function() {
            let index = 1,
                max = 4,
                length = 5;
            const hideCells = _ => document.querySelectorAll("#ex3 tr")
            .forEach(({ cells }) => {
                [...cells].forEach(({ style }, i) => i && (style.display = i < index || i >= index + max ? "none" : "") )
            })
            hideCells();
            $(".scroll-table").on("click", "[data-up]", function() {
                index += +this.dataset.up;
                index = Math.max(1, Math.min(length - max, index));
                hideCells()
            })
        });