Making Drupal 8 datetime widgets use human formats
Drupal 8 includes a datetime field type and widget out of the box.
The widget uses the HTML5 date element on supported browsers, providing a polyfill to a text field with jQuery UI's datepicker for browsers that don't yet support HTML5 date inputs.
However - HTML5 date formats always work in ISO8601 format - ie YYYY-MM-DD - which isn't very user-friendly for those using Firefox and Internet Explorer.
Luckily, with a few tweaks you can easily swap this into DD/MM/YYYY format for those browsers and then switch it back server side into the format Drupal expects.
