Form data - Files > XHR

gistfile1.txt

var formData = new FormData()
for (var i = 0; i < files.length; i++){
	formData.append('file', files[i]);
}

//new post a new XHR request
var xhr = new XMLHttpRequest();
xhr.open('POST', url);
xhr.upload.onprogress = function (event){
	if (event.lengthComputable) {
		var complete = (event.loaded / event.total * 100 | 0);
		progress.value = complete; 
	}
}

xhr.send(formData);