for (var x = 0; x < ins; x++) {
form_data.append("files[]", document.getElementById('certificates').files[x]);
}
for (var x = 0; x < ins; x++) {
form_data.append("files[]", document.getElementById('certificates').files[x]);
}
var form_data = new FormData();
var ins = document.getElementById('certificates').files.length;