var timeoutID1;
var timeoutID2;

function scroll_down(idObj) {
    timeoutID1 = setInterval("scroll(document.getElementById(\""+idObj+"\"), +2)", 50);
}

function scroll_up(idObj) {
    timeoutID2 = setInterval("scroll(document.getElementById(\""+idObj+"\"), -2)", 50);
}

function scroll(obj, change) {
    obj.scrollTop += change;
    if (obj.scrollTop < 0) {
        obj.scrollTop = 0;
    }
}

function stop() {
    
    if (timeoutID1 != undefined) {
      clearInterval(timeoutID1);
    }
    
    
    if (timeoutID2 != undefined) {
      clearInterval(timeoutID2);
    }
}