When you press the submit button first prevent the default form submission, then log all the data in the form to the console.
let formData = new FormData($form);
for (let entry of formData.entries()) {
console.log(entry);
}
let formData = new FormData($form);
let data = Object.fromEntries(formData);
console.log('data', data);
Read the docs here: https://developer.mozilla.org/en-US/docs/Web/API/FormData/FormData