问Nodejs XMLHttpRequest上传文件不能使用Formdata？

由于跨域问题，在后台非浏览器环境下使用nodejs+XMLHTTPREQUEST上传文件。同样代码在浏览器环境下是没有问题的。

var url = "http://" + connectedTo+'/upload';

xhtr2.open('POST',url,true);

xhtr2.setRequestHeader('Content-Type','multipart/form-data; boundary=xxxxxxx');

xhtr2.onload = function(){

}

var formData=new FormData();

xhtr2.send(formData);

错误日志如下:

node_modules\xhr2\lib\xhr2.js:1196

throw new Error(`Unsupported send() data ${data}`);

^

Error: Unsupported send() data [object FormData]

at XMLHttpRequestUpload._setData (..\node_modules\xhr2\lib\xhr2.js:1196:15)

at XMLHttpRequest._sendHttp (..\node_modules\xhr2\lib\xhr2.js:458:21)

at XMLHttpRequest.send (..\node_modules\xhr2\lib\xhr2.js:278:18)