//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("\n");
            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