xmlhttprequest请求

var xhr = new XMLHttpRequest();
xhr.open('POST', 'http://posttestserver.com/post.php');
xhr.onload = () => {
if (xhr.status !== 200) {
AlertIOS.alert(
'Upload failed',
'Expected HTTP 200 OK response, got ' + xhr.status
);
return;
}

// upload succeeded
...
};
var formdata = new FormData();
formdata.append(photo, {type: "image/jpeg", name: ____, uri: ______ });

if (xhr.upload) {
xhr.upload.onprogress = (event) => {
console.log('upload onprogress', event);
if (event.lengthComputable) {
this.setState({uploadProgress: event.loaded / event.total});
}
};
}
xhr.send(formdata);