butter-portal/app/static/time.js

document.addEventListener('DOMContentLoaded', () => {
var currentTime = new Date();
const $myDatetimeField =  document.querySelector('#butterbox_date')
    console.log(currentTime.toISOString().substring(0, 19));
    $myDatetimeField.value = currentTime.toISOString().substring(0, 19) + 'Z';

});