jQuery Datepicker Widget

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

Example: date_picker.html

Markup:

<form action="https://cscie12.dce.harvard.edu/echo">
  <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>