function random_all()
{
var myrandom=Math.round(Math.random()*(document.links.length-1))
window.open(document.links[myrandom].href,"2")
}

function checksel()
{
var x=document.getElementsByName("id");
var issel=false;
var j=0;  for(var i=0;i<x.length;i++)
    {
    if(x[i].checked)
      {issel=true;j=j+1}
    }
    if (issel==false)
      {alert("请至少选择一首歌曲!");return false;}
    if (j>30){alert("最多只能选择30首歌曲!");return false;}
}

function   check(str,num)
{
  var checkednum=0;
  var a=document.getElementsByName(str);
  var n=a.length;
  for(var i=0;i<n;i++) 
    if(a[i].checked){checkednum++;}
  if(checkednum>num){alert("最多只能选择30首!");return false;}
  else{return true;}
}

  function checkall(form)
 {
    var x=document.getElementsByName("id");
    for (var i=0;i<x.length;i++)
    {x[i].checked=false;}
	   for (var i=0;i<form.id.length;i++)
	     {form.id[i].checked=true;}
 }
	

  function checknone(form)
  {
    var obj=document.getElementsByName("id");	   for (var i=0;i<obj.length;i++)
	    {obj[i].checked=false;}
  }

function playsel()
{
  var obj=document.getElementsByName("id");
  var vv="";
  for(var i=0;i<obj.length;i++)
  {
    if (obj[i].checked==true)
      vv+=obj[i].value+",";
  }
  vv=vv.substring(0,vv.length-1);
  form1.action="http://www.446655.com/shanggan/playsong.asp?id="+vv;
  form1.submit();
}