A jQuery function which returns a subset of the given element(s) (jQuery object), where each element returned has the data attribute specified and thatdata attribute's value is equal to that of the second parameter (if one was given)

filterByDataAttribute.jquery.js

/**
 * @param dataAttributeName string
 * @param desiredDataAttributeValue string (optional)
 * (desiredDataAttributeValue must be a string, strict comparison is done with data attribute value)
 * 
 * @author: adam-lynch
 */
$.fn.filterByDataAttribute = function(dataAttributeName, desiredDataAttributeValue){
    return $(this).filter(function() {        
        return desiredDataAttributeValue && $(this).data(dataAttributeName) === desiredDataAttributeValue
                || !desiredDataAttributeValue && $(this).is('*[data-'+dataAttributeName+']');
    });
};