var subs_array = new Array("sub1","sub2","sub3", "sub4", "sub5", "sub6", "sub7", "sub8", "sub9", "sub10", "sub11", "sub12", "sub13", "sub14", "sub15", "sub16", "sub17", "sub18", "sub19", "sub20");// 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 = "";
}