Where to add code

I’m trying to add the following code into contact form 7 in order to create a file upload progress bar. Can someone help with how to do that? The original code can be found here: https://codepen.io/PerfectIsShit/pen/zogMXP

Javascript:

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(“file1”, file); 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”, “file_upload_parser.php”); // 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 = (event.loaded / event.total) * 100; _(“progressBar”).value = Math.round(percent); _(“status”).innerHTML = Math.round(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”; }

HTML:

<h2>HTML5 File Upload Progress Bar Tutorial</h2> <form id=”upload_form” enctype=”multipart/form-data” method=”post”> <input type=”file” name=”file1″ id=”file1″ onchange=”uploadFile()”><br> <progress id=”progressBar” value=”0″ max=”100″ style=”width:300px;”></progress> <h3 id=”status”></h3> <p id=”loaded_n_total”></p> </form>