While it would be great if we could just use native Datepickers in our websites, in reality it just does not work this way. Some browsers don't support it at all (even modern ones like Firefox!), and even those desktop browsers that support it have a rather lacking user experience (Chrome).
PikadayResponsive uses Modernizr to detect touch and type="date" support and includes either a native date field or a Pikaday-input. Additionally, you can define how the output of the field should be (for example you might want the value of the field to be a UNIX timestamp, not a string) as well as how the date should be displayed in the field. This way you have full control of your date, can use the included localisation features of Moment.js and can provide a truly responsive datepicker experience for all devices.