jQuery Datepicker Widget

jQuery has plugins that will provide an unobtrusive "calendar" widget for picking dates.

Example: date_picker.html

Markup:

<form action="https://cs12.net/form/submit.php">
 <p>
   Enter a start date: <input class="date" type="text" size="32" name="startdate" id="startdate" />
 </p>
 <p>
   Enter an end date: <input class="date" type="text" size="32" name="enddate" id="enddate" />
 </p>
 <input type="submit"/>
</form>

CSS amd JS:

<link rel="stylesheet"
 href="https://ajax.googleapis.com/ajax/libs/jqueryui/1.12.1/themes/smoothness/jquery-ui.css"
  media="all" />
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"
   ></script>
<script
   src="https://ajax.googleapis.com/ajax/libs/jqueryui/1.12.1/jquery-ui.min.js"
   ></script>
<script >
 $(document).ready(function(){
   $('input.date').datepicker();
 })
</script>