Update HTML Dropdown List based on Google Calendar Query
<p>I'm trying to create an HTML form that involves the user selecting a start and end date. Once they selected a date range, I want to have a HTML dropdown update based on whether or not the resource is busy/free on gCal. Is there any way to update the dropdown menu by querying gCal? I'm not really sure how to link the HTML form element to Google service like Calendar. </p>

<p>Here is the sample HTML I am working with:</p>

<pre><code> &lt;form action="action_page.php"&gt;
            &lt;!-- Query for start date --&gt;
            Start Date:
            &lt;input type="date" name="startdate", align="center"&gt;
            &lt;br/&gt;
            &lt;!-- Query for end date --&gt;
            End Date:
            &lt;input type="date" name="enddate", align="center"&gt;
            &lt;input type="submit"&gt;
            &lt;br&gt;&lt;br&gt;
            &lt;!-- Query for  --&gt;
            &lt;form action="action_page.php"&gt;
              &lt;select name="cars"&gt;
                &lt;option value="volvo"&gt;Volvo&lt;/option&gt;
                &lt;option value="saab"&gt;Saab&lt;/option&gt;
                &lt;option value="fiat"&gt;Fiat&lt;/option&gt;
                &lt;option value="audi"&gt;Audi&lt;/option&gt;
              &lt;/select&gt;
            &lt;/form&gt;
</code></pre>

<p>Thanks! Any help would be very much appreciated. </p>