如题，我这样写有错误，不知道要怎样修改

<SCRIPT language="JavaScript">
<!--
var sound1="images/1.mid"
var sound2="images/2.mid"
var sound3="images/3.mid"
var x=Math.round(Math.random()*3)
if (x==0) x=sound1
else if (x==1) x=sound2
else x=sound3
if (navigator.appName=="Microsoft Internet Explorer")
document.write('<bgsound src='+'"'+x+'"'+' loop="infinite"'+'"id="soundctl"'+' >')
else
document.write('<embed src='+'"'+x+'"'+'hidden="true" border="0" width="20" height="20" autostart="true"

loop="true"'+'"id="soundctl"'+' >')

function   dosound()   
  {   
  if(document.getElementById("soundctl").src!="")   
  {   
  document.getElementById("soundctl").src=""   
  }   
  else   
  {   
  document.getElementById("soundctl").src=x   
  }   
   
  }   

//-->
</SCRIPT>
  <input   type=button   onclick="dosound()"   value="test     bgsound">

想了很久都想不错