document.onclick=check;

function check(e){ 
var target = (e && e.target) || (event && event.srcElement);
var obj = document.getElementById('d1'); 
var obj2 = document.getElementById('d2'); 
checkParent(target)?obj.style.display='none':null; 
target==obj2?obj.style.display='block':null; 
} 

function checkParent(t){ 
while(t.parentNode){ 
if(t==document.getElementById('d1')){ 
return false
} 
t=t.parentNode
} 
return true 
}