Just pass some sort of value whenever the button you want is clicked. For instance:
ob.addEventListener("click",function() {onCl1(1)});
ob1.addEventListener("click",function() {onCl1(1)});
var i;
function onCl1(value){
i += value;
if(i == 2){
//do this
}
}
So basically once these two buttons are clicked the value will equal 2 and trigger whatever you want.