AJAX上传后$ _FILES为空

Question

I'm developing a simple script to upload a file through AJAX but after form submission, the variable $_FILES is completely empty, although the file exists within php://input, but with no simple way to extract only the file. Anyone knows the reason and/or solution to this problem?

I've checked all the common solutions. enctype="multipart/form-data" rights to temp folder form-tags closing doublequotations and the output of the file-input in JS

Nothing has solved my problem.

RED This is NOT jquery, and I haven't found a duplicate in 24h. So please don't mark as duplicate unless you're sure it is one.

HTML

<form action="upload.php" method="POST" enctype="multipart/form-data" id="testf">
<input type="file" name="file" accept=".jpg">
<input type="submit" value="Skicka">
</form>

JavaScript

let data = document.querySelector("#testf");
data.onsubmit = function() {
    var http = new XMLHttpRequest();
    http.open("upload.php", data.action);
    http.onreadystatechange = function () {
        console.log(http.response);
    }
    http.setRequestHeader("Content-type", data.enctype);
    http.send(new FormData(data));
    event.preventDefault();
    return false;
}

PHP

<?php
var_dump($_FILES);
?>

This should print the contents of my file, but

array(0) {}

is all I get. Request payload is:

------WebKitFormBoundaryZVGq8suqFUUSFDtW
Content-Disposition: form-data; name="file"; filename="david.jpg"
Content-Type: image/jpeg


------WebKitFormBoundaryZVGq8suqFUUSFDtW--

Answer 1

You have a problem with your JavaScript method XMLHttpReqest. It takes at least two parameters: Method and url. Full parameters are:method, url, async, user, password

Change your code from:

 http.open("upload.php", data.action);

To:

 http.open("post", data.action );

Update: Also remove

http.setRequestHeader("content-type", "multipart/form-data")

Form data already sets its headers for content-type.