Form submit fil med ajax

var form = document.getElementById('file-form');
var fileSelect = document.getElementById('file-select');
var uploadButton = document.getElementById('upload-button');

form.addEventListener("onsubmit", function(event) {
   
    event.preventDefault(event);
   
    var files = fileSelect.files;
    var formData = new FormData();
   
    // Loop through each of the selected files.
    for (var i = 0; i < files.length; i++) {
          var file = files[i];
       
          // Check the file type.
          if (!file.type.match('image.*')) {
            continue;
          }
       
          // Add the file to the request.
          formData.append('photos[]', file, file.name);
    }
       
    // Files
    formData.append(name, file, filename);
   
    // Blobs
    formData.append(name, blob, filename);
   
    // Strings
    formData.append(name, value);
       
    var xhttp = new XMLHttpRequest();
   
    xhttp.onreadystatechange = function() {
       
       
          if (this.readyState == 4 && this.status == 200) { //succes
           
            alert('Uploade succes');
           
        } else if(this.readyState == 4 && (this.status == 403 || this.status == 404 || this.status == 401 || this.status == 408)) { //error
       
       
        } else if(this.readyState <4) { //pending
           
        }
    };
 
    xhttp.open('POST', 'actions/uploadbillede.php', true);
    xhttp.send(formData);
   
}

<form id="file-form" >
<input type="file" id="file-select" multiple>
<input type="submit" id="upload-button" >
</form>

var form = document.getElementById('file-form');
var fileSelect = document.getElementById('file-select');
var uploadButton = document.getElementById('upload-button');

form.addEventListener("submit", function(event) {
   
    event.preventDefault();
   
    var files = fileSelect.files;
    var formData = new FormData();
   
    // Loop through each of the selected files.
    for (var i = 0; i < files.length; i++) {
          var file = files[i];
       
          // Check the file type.
          if (!file.type.match('image.*')) {
            continue;
          }
       
          // Add the file to the request.
          formData.append('photos[]', file, file.name);
    }
       
    // Files
    formData.append(name, file, filename);
   
    // Blobs
    formData.append(name, blob, filename);
   
    // Strings
    formData.append(name, value);
       
    var xhttp = new XMLHttpRequest();
   
    xhttp.onreadystatechange = function() {
       
       
          if (this.readyState == 4 && this.status == 200) { //succes
           
            alert('Uploade succes');
           
        } else if(this.readyState == 4 && (this.status == 403 || this.status == 404 || this.status == 401 || this.status == 408)) { //error
       
       
        } else if(this.readyState <4) { //pending
           
        }
    };
 
    xhttp.open('POST', 'actions/uploadbillede.php', true);
    xhttp.send(formData);
   
});