jquery循环通过json

嗨，我试图像这样循环一个json文件：

$.each(data.playlists.playlist, function(i, item) { $("#contentC").append('
' + item.id + '
'); $("#contentC").append('
' + item.title + '
'); $("#contentC").append('
' + item.url + '
'); } ); 

JSON：

 { "playlists":{ "playlist":[ { "id":"8391802", "title":"Second Playlist", "description":"", "date":"2011-03-06T18:53:33", "size":"10", "duration":"2267", "streamable":"0", "creator":"http:\/\/www.last.fm\/user\/jon21021985", "url":"http:\/\/www.last.fm\/user\/jon21021985\/library\/playlists\/4zv5m_second_playlist", "image":[ { "#text":"", "size":"small" }, { "#text":"", "size":"medium" }, { "#text":"", "size":"large" }, { "#text":"", "size":"extralarge" } ] }, { "id":"8372409", "title":"All-american Rejects", "description":"", "date":"2011-02-28T13:30:01", "size":"6", "duration":"785", "streamable":"0", "creator":"http:\/\/www.last.fm\/user\/jon21021985", "url":"http:\/\/www.last.fm\/user\/jon21021985\/library\/playlists\/4zg6x_all-american_rejects", "image":[ { "#text":"", "size":"small" }, { "#text":"", "size":"medium" }, { "#text":"", "size":"large" }, { "#text":"", "size":"extralarge" } ] } ], "@attr":{ "user":"jon21021985" } } } 

问题是如果只有一个播放列表，数据会发生变化，那么我会得到“未定义”

  { "playlists":{ "playlist":{ "id":"1319510", "title":"Untitled", "description":"", "date":"2007-10-18T12:17:58", "size":"1", "duration":"345", "streamable":"0", "creator":"http:\/\/www.last.fm\/user\/john", "url":"http:\/\/www.last.fm\/user\/john\/library\/playlists\/sa52_", "image":[ { "#text":"", "size":"small" }, { "#text":"", "size":"medium" }, { "#text":"", "size":"large" }, { "#text":"", "size":"extralarge" } ] }, "@attr":{ "user":"john" } } } 

Answer 1

 if($.isArray(data.playlists.playlist)) { $.each(data.playlists.playlist, function(i, item) { displayPlayList(item) ); } else { displayPlayList(data.playlists.playlist); } //this way of appending an element is very poor coding practice but //i have done this way, because u yourself have written this // if u want then i can suggest you, how can u optimize this code function displayPlayList(item) { $("#contentC").append('
' + item.id + '
'); $("#contentC").append('
' + item.title + '
'); $("#contentC").append('
' + item.url + '
'); } } 

编辑

正如Emmet所指出的，你应该总是返回数组。 但是在你使用派对json服务并且他们以这种格式返回数据的情况下它是可以接受的，那么你无能为力