js的sleep功能

function myrefresh() 
{ 
sleep(500); 
//window.location.reload(); 
parent.location.reload();  
} 


function sleep(numberMillis) {    
var now = new Date();    
var exitTime = now.getTime() + numberMillis;   
while (true) { 
now = new Date();       
if (now.getTime() > exitTime) 
return;    
} 
}