function creatDialog() { 
  // 获取屏幕的宽度和高度 
  var wid=document.body.clientWidth; 
  var hei=document.body.clientHeight; 
 
  //根据已有dialog计算下一个dialog位置 
  var obj=document.getElementsByClassName("dialog"); 
  //5和10为间距 
  var top=5; 
  var left=10; 
 
  if(obj.length!=0){ 
    //不是第一次生成 
    var h=parseInt(hei/(274+5));//求出总行数 
    var w=parseInt(wid/(300+10));//求出总列数 
    var n=parseInt(obj.length/h);//位于第n+1列 
    if(n+1<=w){ 
      var m=obj.length%h//位于第m+1行 
      top=(274+5)*m+5; 
      left=(300+10)*n+10; 
    }else { 
      //屏幕满了移除所有对象，从新开始 
      removeDialog(); 
       top=5; 
       left=10; 
    } 
 
  } 
//生成dialog 
  var dialog=document.createElement('div'); 
  dialog.className="dialog"; 
  dialog.id="dialog"+obj.length; 
  dialog.style.position="absolute"; 
  dialog.style.marginLeft=left+"px"; 
  dialog.style.marginTop=top+"px"; 
  dialog.style.width="300px"; 
  dialog.style.height="274px"; 
  dialog.style.border="solid 1px"; 
  dialog.style.backgroundColor="#FF0000"; 
  document.body.appendChild(dialog); 
} 
 
function removeDialog() { 
  var obj=document.getElementsByClassName("dialog"); 
  var num=obj.length; 
  for(var i=0;i