Toggle a property of a breadcrumb navigation from "true" to "false"

How do I toggle the data-disabled property of the following breadcrumb navigation from "true" to "false":

<ul class="breadcrumb" 
    	id="rfrbc"
        data-numbers="true" 
        data-connect="rfrcontent"
        data-disabled="true">
        <li><a href="#">Section1</a></li>
        <li><a href="#">Section2</a></li>
        <li><a href="#">Section3</a></li>
    </ul>
    <div id="rfrcontent">
        <div id="rfrsection1">    
                <?php include "Section1.php";?>  
        </div>
        <div id="rfrsection2">    
			    <?php include "Section2.php";?>  
        </div>	
        <div id="rfrsection3">    
			    <?php include "Section3.php";?>  
        </div>
    </div>

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Basically what I would like to do is that in response to some other event, I would like to change the data-disabled property from "true" to "false", thereby enabling the breadcrumb navigation.  How would I do that?  Thanks.