HTML5 brings great new features which will ease development. However, currently there is a gap between browsers that support HTML5 attributes and those who do not. As of October around 60% of desktop browsers and 80% of mobile devices are HTML5 compliant. This means developers still need support the additional 40% which fallback techniques.
HTML5 date input field
A good example is the new date input field. If your browser is HTML5 compliant it generate a date picker for you to use automatically, thus only requiring the developer to create the input field as so:
<input name="start_date" type="date" placeholder="mm/dd/yyyy" />
Providing a fallback
The input field has classes attached that are from the bootstrap 3 library. These libraries add a hint of design to the end result.
<div class="input-group date" id="startDatetime"> <input name="end_date" type="date" placeholder="mm/dd/yyyy" class="form-control"/> <span id="endDateIcon" class="input-group-addon"> <span class="glyphicon glyphicon-calendar"></span> </span> </div>
A example of this project can be seen on JSFiddle.