基于ajax后台返回的数据为空前台显示出现undefined的解决方法_AJAX相关_

 $(document).ready(function () { $("#rankTable tbody").html(""); var id = 1; $.ajax({ url:"bookInfo/bookInfo_rank.action", type:"POST", data:{}, dataType:"json", success:function (data) { $(data).each(function(i,item) { var index = id++; var bookId = item.bookId; var bookName = item.bookName; var author = item.author; //判断是否为空出现undefined； var translator = (item.translator==undefined ?"":item.translator); var ISBN = item.ISBN; var press = item.press; var page = item.page; var bookCase = item.bookCase; var totalNum = item.totalNum; var stock = item.stock; var borrowNum = item.borrowNum; var typeName = item.typeName; var str = ' ' + '' + index + '' + '' + bookId + '' + '' +bookName + '' + '' + author+ '' +''+translator+ '' +''+ISBN+ '' +''+press+ '' +''+page+ '' +''+bookCase+ '' +''+totalNum+ '' +''+stock+ '' +''+borrowNum+ '' +''+typeName+ ''; $("#rankTable tbody").append(str); str = ""; }) }, error:function(XMLHttpRequest, textStatus, errorThrown){ alert("系统异常，请稍后重试！"); alert(XMLHttpRequest.status); alert(XMLHttpRequest.readyState); alert(textStatus); } }) });