Uploading files using XMLHttpRequest

Question

I'm trying to use a drag and drop plugin in javascript to upload files using ajax.

<script>
DnD.on('#drop-area', {

'drop': function (files, el) {
   el.firstChild.nodeValue = 'Drag some files here.';
   var names = [];
   [].forEach.call(files, function (file, i) {
      names.push(file.name + ' (' + file.size + ' bytes)');

   var xhr = new XMLHttpRequest();
   xhr.open('POST','upload.php');
   xhr.setRequestHeader("Content-type", "multipart/form-data"); 
   xhr.send(file);
   console.log(xhr.responseText);
});
document.querySelector('#dropped-files p i').firstChild.nodeValue = names.join(', ');
}
});
</script>

And here's upload.php:

<?php
print_r($_POST);
?>

Basically I haven't written the script to upload the file yet because I'm still figuring out how can I have access to the data that I've sent through JavaScript. Can you guide me on what to do next? How do I access the file from upload.php.

Solution

Try to use FormData instead of xhr:

var formData = new FormData();
formData.append("thefile", file);
xhr.send(formData);

You have access to your file with this array:

<?php var_dump($_FILES["thefile"]); ?> 

See more: http://www.w3schools.com/php/php_file_upload.asp