//here you place the ids of every element you want.
var ids=new Array('a1','a2','a3','a4','a5','a6','a7','a8');

function switchid(id){	
	hideallids();
	showdiv(id);
}

function hideallids(){
	//loop through the array and hide each element by id
	for (var i=0;i<ids.length;i++){
		hidediv(ids[i]);
	}		  
}
function showallids(){
	//loop through the array and hide each element by id
	for (var i=0;i<ids.length;i++){
		showdiv(ids[i]);
	}		  
}

function hidediv(id) {
	//safe function to hide an element with a specified id
	if (document.getElementById) { // DOM3 = IE5, NS6
		document.getElementById(id).style.display = 'none';
	}
	else {
		if (document.layers) { // Netscape 4
			document.id.display = 'none';
		}
		else { // IE 4
			document.all.id.style.display = 'none';
		}
	}
}

function showdiv(id) {
	//safe function to show an element with a specified id
		  
	if (document.getElementById) { // DOM3 = IE5, NS6
		document.getElementById(id).style.display = 'block';
	}
	else {
		if (document.layers) { // Netscape 4
			document.id.display = 'block';
		}
		else { // IE 4
			document.all.id.style.display = 'block';
		}
	}
}
function addOnloadEvent(fnc){
  if ( typeof window.addEventListener != "undefined" )
    window.addEventListener( "load", fnc, false );
  else if ( typeof window.attachEvent != "undefined" ) {
    window.attachEvent( "onload", fnc );
  }
  else {
    if ( window.onload != null ) {
      var oldOnload = window.onload;
      window.onload = function ( e ) {
        oldOnload( e );
        window[fnc]();
      };
    }
    else 
      window.onload = fnc;
  }
}
addOnloadEvent(hideallids);