document.forms['myFormId'].addEventListener('submit', (event) => {
event.preventDefault();
// TODO do something here to show user that form is being submitted
fetch(event.target.action, {
method: 'POST',
body: new URLSearchParams(new FormData(event.target)) // event.target is the form
}).then((resp) => {
return resp.json(); // or resp.text() or whatever the server sends
}).then((body) => {
// TODO handle body
}).catch((error) => {
// TODO handle error
});
});