FormData object, doesn't seem to be uploading my file…

Question

Im following this guide to use aJax to upload an image, mainly so I can have a progress bar. But for some reason the PHP script doesn't seem to receive a file!

Here is my JavaScript:

function submitFile() {
    var form = document.forms.namedItem("imageUpload");
    var formData = new FormData(form);

    var xhr = new XMLHttpRequest();
    xhr.open("POST", "php/uploadImage.php", true);
    xhr.onload = function(e) {
        if (xhr.status == 200) {
            console.log("uploaded!");
            doc("imageResponse").innerHTML = xhr.responseText;
        } else {
            console.log("error!");
            doc("imageResponse").innerHTML += "Error " + xhr.status + " occurred when trying to upload your file.<br \/>";
        }
    };

    //Progress
    /*
    xhr.upload.onprogress = function(e) {
        if (e.lengthComputable) {
            var currentPercentage = Math.round(e.loaded / e.total * 100);
            document.getElementById("imageUpload").innerHTML = "UPLOAD IMAGE " + currentPercentage + "%";
            document.getElementById("imageUpload").style.backgroundSize = currentPercentage + "% 100%";
        }
    };
    */

    //Send data
    xhr.send(formData);
}

And here is my PHP file which receives the file:

<?php
session_start();
print_r($_FILES);
?>

Currently that PHP file is returning an empty Array... it should have my file!

Array ( )

Answer 1

I managed to fix my code, here is the working version for anyone with the same problem. I decided to make a new form using JavaScript and append the file field value to this new form.

I did this mainly for my situation.

function submitFile(file,buttonId) {
    //Generate a new form
    var f = document.createElement("form");
    f.setAttribute("method", "POST");
    f.setAttribute("enctype", "multipart/form-data");

    //Create FormData Object
    var formData = new FormData(f);

    //Append file
    formData.append("image", file.files[0], "image.jpg");

    var xhr = new XMLHttpRequest();
    xhr.open("POST", "php/uploadImage.php", true);
    xhr.onload = function(e) {
        if (xhr.status == 200) {
            document.getElementById(buttonId).innerHTML = "UPLOAD COMPLETE";
            //console.log("uploaded!");
        } else {
            //console.log("error!");
            alert("Error " + xhr.status + " occurred when trying to upload your file");
        }
    };

    //Progress
    xhr.upload.onprogress = function(e) {
        if (e.lengthComputable) {
            var currentPercentage = Math.round(e.loaded / e.total * 100)-1;
            document.getElementById(buttonId).innerHTML = "UPLOAD IMAGE " + currentPercentage + "%";
            document.getElementById(buttonId).style.backgroundSize = (currentPercentage+1) + "% 100%";
            if (currentPercentage==99) {
                document.getElementById(buttonId).innerHTML = "Processing image";
            }
        }
    };

    //Send data
    xhr.send(formData);
}