Database populated chained drop down menu
<p>I have created this JSP page in which all the drop down menus are populated from database.  This functionality works fine I've tested it.  But now I need to add a function so the third drop down menu (which is Forecast ISC)  only becomes visible when I select a certain field from first menu which is "Type" .So far I haven't created any java script because that's what i need help with! Any suggestions or comment will help!</p>

<pre><code>  &lt;form:form action="/analysis/analysisSummary" modelAttribute="shipData"
    method="POST" onChange = 'checkType()'&gt;
    &lt;br&gt;
    &lt;table width="100%"&gt;
        &lt;tr&gt;
            &lt;td width="20%"&gt;&lt;/td&gt;
            &lt;td width="20%"&gt;Type:&lt;form:select id="type" path="type"&gt;
            &lt;form:option value="All"&gt;------ All ------   &lt;/form:option&gt;
        &lt;form:options items="${analysisEvents}" itemLabel="description"
                        itemValue="code" /&gt;
                &lt;/form:select&gt;
            &lt;/td&gt;


            &lt;td width="20%"&gt;Forecast ISC:&lt;form:select id="iscCode"
                    path="iscCode"&gt;
                    &lt;form:option value="All"&gt;ALL&lt;/form:option&gt;
                    &lt;form:options items="${iscCodes}" /&gt;
                &lt;/form:select&gt;
            &lt;/td&gt;

            &lt;td width="30%"&gt;&lt;div style="visibility: hidden"&gt;
                    Actual ISC: &lt;form:select id="sctry"
                    path="iscCode"&gt;
                    &lt;form:option value="All"&gt;ALL&lt;/form:option&gt;
                    &lt;form:options items="${iscCodes}" /&gt;
                &lt;/form:select&gt;
                &lt;/div&gt;
            &lt;/td&gt;
</code></pre>

<p>HTML:</p>

<pre><code>       &lt;form id="shipData" onChange="checkType()" action="/analysis/analysisSummary" method="POST"&gt;
    &lt;br&gt;
    &lt;table width="100%"&gt;
        &lt;tr&gt;
            &lt;td width="20%"&gt;&lt;/td&gt;
            &lt;td width="20%"&gt;Type:&lt;select id="type" name="type"&gt;
                    &lt;option value="All"&gt;------ All ------&lt;/option&gt;
                    &lt;option value="U"&gt;Unanalyzed&lt;/option&gt;&lt;option value="H"&gt;Pending&lt;/option&gt;&lt;option value="F"&gt;True Hit&lt;/option&gt;&lt;option value="C"&gt;Return Reason&lt;/option&gt;&lt;option value="S"&gt;Parcel Returned&lt;/option&gt;&lt;option value="T"&gt;Long Term Pending&lt;/option&gt;&lt;option value="Z"&gt;Value &amp;gt;2500&lt;/option&gt;
                &lt;/select&gt;
            &lt;/td&gt;


            &lt;td width="20%"&gt;Forecast ISC:&lt;select id="iscCode" name="iscCode"&gt;
                    &lt;option value="All"&gt;ALL&lt;/option&gt;
                    &lt;option value="JFK"&gt;JFK&lt;/option&gt;&lt;option value="LAX"&gt;LAX&lt;/option&gt;&lt;option value="MIA"&gt;MIA&lt;/option&gt;&lt;option value="ORD"&gt;ORD&lt;/option&gt;&lt;option value="SFO"&gt;SFO&lt;/option&gt;
                &lt;/select&gt;
            &lt;/td&gt;

            &lt;td width="30%"&gt;&lt;div style="visibility: hidden"&gt;
                    Actual ISC: &lt;select id="sctry" name="iscCode"&gt;
                    &lt;option value="All"&gt;ALL&lt;/option&gt;
                    &lt;option value="JFK"&gt;JFK&lt;/option&gt;&lt;option value="LAX"&gt;LAX&lt;/option&gt;&lt;option value="MIA"&gt;MIA&lt;/option&gt;&lt;option value="ORD"&gt;ORD&lt;/option&gt;&lt;option value="SFO"&gt;SFO&lt;/option&gt;
                &lt;/select&gt;
                &lt;/div&gt;
            &lt;/td&gt;
            &lt;td width="8%"&gt;&lt;/td&gt;
        &lt;/tr&gt;
    &lt;/table&gt;
    &lt;br&gt;
    &lt;table width="100%"&gt;
        &lt;tr&gt;

            &lt;td width="20%"&gt;&lt;/td&gt;
</code></pre>
