The example
This is a very simple example showing you how to do a live demo in MDN. For more information, see Live samples.
<form> <label>Try me<input type="text" name="name"></label> <input type="submit" value="go"> </form>
form { border-radius: 10px; background: powderblue; }
var f = document.querySelector('form'); f.addEventListener('submit', function(ev) { ev.preventDefault(); document.querySelectorAll('input')[1].value = 'sending'; }, false);