E_SIZE = 20;

    document.getElementById('start_left').onclick = () => {
        if (leftOffset > 0) {
            leftOffset = 0;
            load(currentLeftTable, leftOffset);
        }
    };
    document.getElementById('prev_left').onclick = () => {
        if (leftOffset > 0) {
            leftOffset = Math.max(leftOffset - PAGE_SIZE, 0);
            load(currentLeftTable, leftOffset);
        }
    };
    document.getElementById('next_left').onclick = () => {
        if (leftOffset < currentLeftTabl