Question

$("#id_btnquizzestwo").click(function() {
    $temp = $("#rightsideeightone").is(":visible");     
    if($temp) {
        $("#rightsideeightone").css('display') = 'none';    
    }
})

The rightsideeightone division is not being hidden.

What to do ?

$("#id_btnquizzestwo").click(function() {
    $temp = $("#rightsideeightone").is(":visible");
    //alert($temp);

    if($temp) {
        $("#rightsideeightone").hide();         
    }

    $temp2 = $("#rightsideeighttwo").is(":hidden");
    //alert($temp2);

    if($temp2) {
        $("#rightsideeighttwo").show();
    }
})

I tried this, the rightsideeighttwo is not being visible. Initialy the rightsideeightone is visible and the rightsideeighttwo is hidden.

<div id="rightsideeight" >
    <div id="id_pollsquizzes" >
        <?php echo '<ul>'; ?>
        <?php
            echo '<li>';
            echo $this->Form->button('Polls',array('type'=>'button','id'=>'id_btnpollstwo'));
            echo '</li>';
            echo '&nbsp&nbsp';

            echo '<li>';
            echo $this->Form->button('Quizzes',array('type'=>'button','id'=>'id_btnquizzestwo'));
            echo '</li>';
            echo '&nbsp&nbsp';
        ?>

    </div>

    <div id="rightsideeightone" style="visibility: visible" >
            ......................
    </div>

    <div id="rightsideeighttwo" style="visibility: hidden" >
            ......................
    </div>

</div>

Answer 1

The line

$("#rightsideeightone").css('display') = 'none';

is incorrect. To change a style property, use this syntax:

$("#rightsideeightone").css('display','none'); 

Checking the visibility isn’t necessary – if the element $(“#rightsideeightone”) is already hidden then hiding it again has no effect, so your function can be written as:

$("#id_btnquizzestwo").click(function() {
        $("#rightsideeightone").css('display','none');
});