How to control coloums element toggle on\off in Visualforce Page

Question

I have the requirement where i have to make bottom td element available if Is This mercer case yes.And if Not it should be invisible.

<table>                     
    <tr>
        <th>
            <span>Is this a Mercer case?</span> 

        </th>
        <td>
            <apex:selectList size="1" value="{!mercerVal}" multiselect="false">
                <apex:selectOptions value="{!mercerOptions}" /> 
            </apex:selectList>
        </td>
        <th>
            <span>Direct Deposit of Cliam Reimbursement</span> 

        </th>
        <td>
            <apex:selectCheckboxes value="{!costContainmentVendorValList}" >
                <apex:selectOptions value="{!costContainmentVendorOptions}" />
            </apex:selectCheckboxes>
        </td>
    </tr>
    <tr>
        <td>
            <br/>
        </td>
    </tr>
</table>

Thanks

Answer 1

A bit of explanation, when you rerender an element, you only actually change the DOM of its children, so you need to wrap your selectCheckboxes in an outer element that, when rerendered, will update the rendered property of the tag itself.

You can modify the selectList and selectOptions as follows:

<apex:selectList ...>
    <apex:selectOptions />
    <apex:actionSupport event="onchange" rerender="deposit" />
</apex:selectList>
...
<apex:outputPanel id="deposit">
    <apex:selectCheckboxes rendered="{!mercerVal == 'Yes'}" ...>
        ...
    </apex:selectCheckboxes>
</apex:outputPanel>