title: how to add date picker inside dialogflow parameters
body: <p>I have a chatbot created in Dialogflow ...and i want to add a calendar date picker in the moment i ask for the date of the meeting for example <a href="https://i.stack.imgur.com/unfyE.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/unfyE.png" alt="this is how is looked now"></a>
  The webhook ( in javascript) related with this intent is : </p>
  
  <pre><code> function makeAppointment (agent) {
  
          const appointmentDuration = 1;// Define the length of the appointment to be one hour.
  
          const dateTimeStart = convertParametersDate(agent.parameters.date, agent.parameters.time,timeZoneOffset);
          const dateTimeEnd = addHours(dateTimeStart, appointmentDuration);
          const appointmentTimeString = getLocaleTimeString(dateTimeStart);
          const appointmentDateString = getLocaleDateString(dateTimeStart);
  
          return createCalendarEvent(dateTimeStart, dateTimeEnd).then(() =&gt; {
              agent.add(` Danke vielmals `);
          }).catch(() =&gt; {
              agent.add(` Es tut mir leid`);
          });
      }
  </code></pre>
  
  <p>This version is used in facebook ...now i'm working for web version of the chatbot( created in angular) .
  What i'm looking is : chatbot ask for parameter date for example ...to display the calendar and user to pick the date from the calendar ( not to type it)</p>
  
  <p>Do you have any idea how to do this ?</p>