prevent default on enter press

/* Jquery method */
$('#form-input').on('keypress', (e) => { 
  const keyPressed = e.keyCode || e.which; 
  if (keyPressed === 13) {
    e.preventDefault();
    return false; 
  }
  /* or */
  return keyPressed !== 13;
});

/* or */
$('#form-input').on('keypress', (e) => return e.keyCode !== 13);

/* HTML Inline */
<form ... onkeydown="return event.keyCode !== 13;">