//提取歌词
function getLyric(url){

var request=null; var lyricLines;  if(window.XMLHttpRequest){     request=new XMLHttpRequest() }else{     request=new ActiveXObject("Microsoft.XMLHTTP"); } request.open("GET",url,true); request.send(); request.onreadystatechange=function(){     if(request.readyState===4){         if(request.status===200){             lyricLines=request.responseText.split("
");             return lyricLines;         }else{             alert("出现错误："+request.status);         }     } };  //返回函数不代表返回函数的返回值，因为返回的函数并没有被执行 //应该返回request.onreadystatechange函数所返回的值 return ?;

}

怎样才能返回lyricLines呢