add: return !!val; 
context:             this['class'] = function(name, htmlnode, xhtmlnode) {                var val = htmlnode.className;                if (val) {                    val = validation.classFilter(val);                     if (val) xhtmlnode.setAttribute('class', val);                } else {                    val = htmlnode.getAttribute("class");                    if (val) val = validation.classFilter(val);                                            if (val) xhtmlnode.setAttribute('class', val);                }            };
meta: 2380	/local1/tlutelli/issta_data/temp/all_js/javascript/2007_temp/2007/2380/a66c86479bb56fb3ba0bdc9c529feb15bcc74096/kupucontentfilters.js/clean/kupu/common/kupucontentfilters.js