класс элементов набора JavaScript
cell.className += (cell.className ? " " : "")+"current_class";
Troubled Termite
cell.className += (cell.className ? " " : "")+"current_class";
var list = document.getElementsByClassName('Qty');
var n;
for (n = 0; n < list.length; ++n) {
list[n].value='100';
}