references [JavaScript snippet]

function change_obj(obj) {
  for (var key in obj) {
    obj[key]=obj[key].toUpperCase();
  }
}

function doesnt_change_str(str) {
  str = str.toUpperCase();
}

function main() {

  var cities = {
    "New York" : "USA",
    "Berne"    : "Switzerland",
    "Munich"   : "Germany",
    "Paris"    : "France",
  };

  var cities_copied = cities;

  change_obj(cities);

  delete cities_copied["Munich"];

  for (var city_name in cities) {
    txt_out(city_name + "=" + cities[city_name]);
  }

  txt_out("----");

  delete cities["New York"];

  for (var city_name in cities_copied) {
    txt_out(city_name + "=" + cities_copied[city_name]);
  }

  txt_out("---");

  if (cities == cities_copied) {
    txt_out("cities == cities_copied");
  }
  else {
    txt_out("not cities == cities_copied");
  }

  if (cities === cities_copied) {
    txt_out("cities === cities_copied");
  }
  else {
    txt_out("not cities === cities_copied");
  }

  // ---

  var name_of_fruit = "banana";

  doesnt_change_str(name_of_fruit);

  txt_out("name_of_fruit: " + name_of_fruit);

}