var subs_array = new Array("sub1");// Put the id's of your hidden divs in this array
function displaySubs(the_sub){
 if (document.getElementById(the_sub).style.display==""){
 document.getElementById(the_sub).style.display = "none";return
  }
  for (i=0;i<subs_array.length;i++){
 var my_sub = document.getElementById(subs_array[i]);
 my_sub.style.display = "none";
 }
  document.getElementById(the_sub).style.display = "";
  }