Image upload ajax don't work

Question

I am trying to do an image file upload with ajax without refreshing the page but the file won't be moved to the specified folder i did very basic file upload php code to avoid errors and develop it later

if($_SERVER["REQUEST_METHOD"]=="POST"){
    $file = $_FILES["uploaded"]
    $target_dir = "user_image/";
    $target_file = $target_dir . basename($_FILES["uploaded"]["name"]);
    move_uploaded_file($_FILES["uploaded"]["tmp_name"],$target_file);
}

My ajax and JavaScript are working fine but there is no image on the target file user_image/

    <script charset="UTF-8">
        function _(id){
            return document.getElementById(id);
        }
        _("file_upload").onchange = function() {
            //_("file_upload").submit();
            var id = _("user_id").innerHTML;
            var file = _("file_upload").files[0];
            var formdata = new FormData();
            formdata.append("file1",file);
            var ajax = new XMLHttpRequest();
            ajax.onreadystatechange =
            function(){
                if(ajax.readyState==4 && ajax.status==200){
                   _("one").remove();
                    var img = document.createElement('img');
                    var first_path = '/user_image/';
                    var path = first_path.concat(id,'.png');
                    img.setAttribute('alt','User image');
                    img.setAttribute('id','one');                        
                    img.setAttribute('src',path);
                    _("user").appendChild(img);  
                    alert("end");
                }    
                else{
                    _("one").remove();
                    var img = document.createElement('img');
                    img.setAttribute('src','/img/loading.gif');
                    img.setAttribute('alt','User image');
                    img.setAttribute('id','one');
                    _("user").appendChild(img);                        
                }
            }
            ajax.open("POST","upload_image.php");
            ajax.send(formdata);
        };

    </script>

Answer 1

You need to change the request header to make this work.

ajax.setRequestHeader("Content-type", "multipart/form-data");