Upload with Vanilla JS

upload.js

function _(el) {
    return document.getElementById(el);
}

function uploadFile() {
    var file = _("file1").files[0];
    // alert(file.name+" | "+file.size+" | "+file.type);
    var formdata = new FormData();
    formdata.append("file", file, "video.mov");
    var ajax = new XMLHttpRequest();
    ajax.upload.addEventListener("progress", progressHandler, false);
    ajax.addEventListener("load", completeHandler, false);
    ajax.addEventListener("error", errorHandler, false);
    ajax.addEventListener("abort", abortHandler, false);
    ajax.open("POST", "http://localhost:5000/profile/upload"); // http://www.developphp.com/video/JavaScript/File-Upload-Progress-Bar-Meter-Tutorial-Ajax-PHP
    //use file_upload_parser.php from above url
    ajax.send(formdata);
}

function progressHandler(event) {
    _("loaded_n_total").innerHTML = "Uploaded " + event.loaded + " bytes of " + event.total;
    var percent = Math.round((event.loaded / event.total) * 100);
    _("progressBar").value = percent;
    _("status").innerHTML = percent + "% uploaded... please wait";
}

function completeHandler(event) {
    _("status").innerHTML = event.target.responseText;
    _("progressBar").value = 0; //wil clear progress bar after successful upload
}

function errorHandler(event) {
    _("status").innerHTML = "Upload Failed";
}

function abortHandler(event) {
    _("status").innerHTML = "Upload Aborted";
}


_('upload_form').addEventListener('submit', (e) => {
    e.preventDefault();
    uploadFile();
});