When input NaN, show 0 instead of "NaN"

wp-content/themes/CreepyTheme/js/money.js

@@ -21,7 +21,9 @@ $(document).ready(function(){
     function calculation(action) {
         var currency = $('.select__currency').attr('currency');
         var dollars = parseInt($('.dollar').val().replace('$', '').replace(',', ''));
+        if(isNaN(dollars)){ dollars = 0; }
         var amount = parseInt($('.input__currency').val().replace(prefixes[currency], '').replace(',', ''));
+        if(isNaN(amount)){ amount = 0; }
         var vypocet = 0;
         switch(action){
             case 'multiple': //From dollar to other