If you need to know how many dimensions are filtered, you can also use the script from the Generic Analysis Template of SAP:
var dimsrow = DS_1.getDimensions();
var count = 0;
dimsrow.forEach(function(element, index) {
/* Check if Filter is set */
if (DS_1.getFilterText(element.name) != "") {
count = count + 1;
}
});
if (count > 0) {
BUTTON_HEADER_FILTER.setText(TEXT_POOL.Filtered + count + "" + ")");
}
else {
BUTTON_HEADER_FILTER.setText(TEXT_POOL.NoFilters);
}
You can find it on the OnResultChanged event of the datasource. You could even combine it with what Mustafa and Alfred suggested 