Javascript: Checking if an object has no properties or if a map/associative-array is empty [duplicate]

Try this:

function isEmpty(map) {
   for(var key in map) {
     if (map.hasOwnProperty(key)) {
        return false;
     }
   }
   return true;
}

Your solution works, too, but only if there is no library extending the Object prototype. It may or may not be good enough.