To use the directive, add datetime="date-format" attribute to your input.
<input type="text" datetime="yyyy-MM-dd HH:mm:ss" ng-model="myDate">
<input type="text" datetime="medium" ng-model="myDate">
<input type="text" datetime="short" ng-model="myDate">
<input type="text" datetime="fullDate" ng-model="myDate">
<input type="text" datetime="longDate" ng-model="myDate">
<input type="text" datetime="mediumDate" ng-model="myDate">
<input type="text" datetime="shortDate" ng-model="myDate">
<input type="text" datetime="mediumTime" ng-model="myDate">
<input type="text" datetime="shortTime" ng-model="myDate">