// here is excel IO API
excelIo.save(json, function (blob) {
　　//blobを作り直す
　　blob = blob.slice(0, blob.size, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet") ;
　　saveAs(blob, fileName);
}, function (e) {
　　// process error
　　console.log(e);
}