10.回调地狱

<div id="app"></div>                                          
<h2>列表数据</h2>
<p class="dp"></p>
<audio src="" controls></audio>

1.ajax嵌套

 var url ='http://192.168.4.18:3000/top/playlist/?cat=华语';
        $.ajax({
            url,
            success:res=>{
                var {name,id} = res.playlists[0]
                $("#app").html(name)
                var listUrl = `http://192.168.4.18:3000/playlist/detail?id=${id}`;
                $.ajax({
                    url:listUrl,
                    success:res=>{
                        var {name,id}=res.playlist.tracks[0]
                        $(".dp").html(name)
                        console.log(id)
                        var musicUrl=`http://192.168.4.18:3000/song/url?id=${id}`
                        $.ajax({
                            url:musicUrl,
                            success:res=>{
                                let src=res.data[0].url;
                                $("audio").attr("src",src)
                            }
                        })
                    }
                })
            }
        })