app.filter('comma2decimal', [
function() { // should be altered to suit your needs
    return function(input) {
    var ret=(input)?input.toString().trim().replace(",","."):null;
        return parseFloat(ret);
    };
}]);

app.filter('decimal2comma', [
function() {// should be altered to suit your needs
    return function(input) {
        var ret=(input)?input.toString().replace(".",","):null;
        if(ret){
            var decArr=ret.split(",");
            if(decArr.length>1){
                var dec=decArr[1].length;
                if(dec===1){ret+="0";}
            }//this is to show prices like 12,20 and not 12,2
        }
        return ret;
    };
}]);

app.directive('price', ['$filter',
function($filter) {
return {
    restrict:'A',
    require: 'ngModel',
    link: function(scope, element, attrs, ngModelController) {
        ngModelController.$parsers.push(function(data) {
            //convert data from view format to model format

            data=$filter('comma2decimal')(data);

            return data;
        });

        ngModelController.$formatters.push(function(data) {
            //convert data from model format to view format

            data=$filter('decimal2comma')(data);

            return data;
        });
    }
};}]);

<script type="application/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/angular-i18n/1.5.0/angular-locale_en-us.min.js"></script>

app.filter('commaToDecimal', function(){
    return function(value) {
        return value ? parseFloat(value).toFixed(2).toString().replace('.', ',') : null;
    };
});

DECIMAL_SEP:".",GROUP_SEP:","

DECIMAL_SEP:",",GROUP_SEP:"."

.filter('dot2comma', [
  function() {
    return function(value) {
      return value.toString().replace(/./g,',');
    };
  }]);