Javascript socket.io的返回值

在这里，我正在为我的网站使用node js和socket.io。我希望在执行下面的函数时返回'newString'的值。现在我在函数内部获得'newString'的正确值。但我需要在函数外部使用它

<script>
function createSocketPlayList(){
    var page            =   'notification_playlist';
    var socket = io.connect('http://localhost:8000', { query: "from=<?php echo $_SESSION['userId']?>&page="+page });
    socket.on('notification_playlist', function (data_playlist) {
        var usersList_playlist    = "";
        var musicTitle            = "";
        var myPlaylist            = "";
        $.each(data_playlist.users_playlist,function(index,user){
                musicTitle        = "<?php echo addslashes($objCommon->html2text($allMyPlayList['music_title']))?>";
                usersList_playlist +=   "{ ";
                usersList_playlist +=   "mp3:'<?php echo SITE_ROOT?>uploads/music/"+user.music_url+"',title:'"+musicTitle+" ',artist:'Sanjeev Darshan | © Eros International Media Ltd',rating:4, buy:'#',price:'0.99',duration:'',cover:'<?php echo SITE_ROOT?>uploads/music/"+user.music_thumb+"',releaseddate:'17-05-2015'";
                usersList_playlist +=   " },";  
        });
        var newString = usersList_playlist.substr(0, usersList_playlist.length-1); 
    });

}
</script>

函数createSocketPlayList（）{
var页面='通知\播放列表'；
var socket=io.connect（'http://localhost:8000“，{query:“from=&page=“+page}”）；
socket.on（'notification_playlist'，函数（data_playlist）{
var usersList_playlist=“”；
var musicTitle=“”；
var myPlaylist=“”；
$.each（数据\播放列表。用户\播放列表，功能（索引，用户）{
musicTitle=“”；
usersList_playlist+=“{”；
usersList_playlist+=“mp3:'uploads/music/”+user.music_url+”，标题：“+musicTitle+”，艺术家：'Sanjeev Darshan |©Eros International Media Ltd'，评级：4，购买：'.#'，价格：'0.99'，持续时间：''，封面：'uploads/music/“+user.music_thumb+”，发布日期：'17-05-2015'；
usersList_playlist+=“}，”；
});
var newString=usersList\u playlist.substr（0，usersList\u playlist.length-1）；
});
}

编辑：我添加了一个额外的功能（updatePlayList），因此您可以将播放列表设置为“out”

您需要重新排列代码，使其具有订阅调用（socket.on）和播放列表生成方法（createSocketPlayList），如下所示：

var page = 'notification_playlist';
var socket = io.connect('http://localhost:8000', { query: "from=<?php echo $_SESSION['userId']?>&page="+page });

socket.on('notification_playlist', updatePlayList);

function updatePlayList(data_playlist) {
    var playlist = createSocketPlayList(data_playlist);
    // Update your list wherever it is on the page.
}

function createSocketPlayList(data_playlist){
    var usersList_playlist    = "";
    var musicTitle            = "";
    var myPlaylist            = "";
    $.each(data_playlist.users_playlist,function(index,user){
            musicTitle        = "<?php echo addslashes($objCommon->html2text($allMyPlayList['music_title']))?>";
            usersList_playlist +=   "{ ";
            usersList_playlist +=   "mp3:'<?php echo SITE_ROOT?>uploads/music/"+user.music_url+"',title:'"+musicTitle+" ',artist:'Sanjeev Darshan | © Eros International Media Ltd',rating:4, buy:'#',price:'0.99',duration:'',cover:'<?php echo SITE_ROOT?>uploads/music/"+user.music_thumb+"',releaseddate:'17-05-2015'";
            usersList_playlist +=   " },";  
    });
    return usersList_playlist.substr(0, usersList_playlist.length-1); 
}

var页面='notification_playlist'；
var socket=io.connect（'http://localhost:8000“，{query:“from=&page=“+page}”）；
socket.on（'notification_playlist'，updatePlayList'）；
函数updatePlayList（数据\播放列表）{
var playlist=createSocketPlayList（数据播放列表）；
//在页面上的任何位置更新列表。
}
函数createSocketPlayList（数据播放列表）{
var usersList_playlist=“”；
var musicTitle=“”；
var myPlaylist=“”；
$.each（数据\播放列表。用户\播放列表，功能（索引，用户）{
musicTitle=“”；
usersList_playlist+=“{”；
usersList_playlist+=“mp3:'uploads/music/”+user.music_url+”，标题：“+musicTitle+”，艺术家：'Sanjeev Darshan |©Eros International Media Ltd'，评级：4，购买：'.#'，价格：'0.99'，持续时间：''，封面：'uploads/music/“+user.music_thumb+”，发布日期：'17-05-2015'；
usersList_playlist+=“}，”；
});
返回usersList\u playlist.substr（0，usersList\u playlist.length-1）；
}