//列出Documents目录下的所有文件，并倒序排列  // 仅iOS支持
                    var filelist1 = application.fso.listfiles('Documents:', application.fso.SORTBY_FILENAME_DES);
                    //遍历所有的文件
                    for(var i1 = 0; i1< filelist1.length; i1++) {
                        if (filelist1[i1].indexOf(".log")>0 || filelist1[i1].indexOf(".log")==0 ){
                            application.fso.deleteFile('Documents:'+filelist1[i1]);
                        }
                    }