Javascript function scope when passing object as a parameter

Question

Hi I have the following javascript code

var skyrimCity = function(object) {
    object = {
      'world': 'whiterun'
    };
  },
  skyrim = function(object) {
    object.world = 'skyrim';
  },

  elderScrolls = {
    'world': 'tamriel'
  };
console.log(elderScrolls); // printed value ? -> {world: "tamriel"}

skyrimCity(elderScrolls);
console.log(elderScrolls); // printed value ? -> {world: "tamriel"}

skyrim(elderScrolls);
console.log(elderScrolls); // printed value ? -> {world: "skyrim"}

Inside skyrim function I changed the value of world but I can see it outside the function as well. I am wondering why the scope of this change propagated outside the function? Is passing an object inside a javascript function always passed as a reference to the original object itself?

Answer 1

Is passing an object inside a javascript function always passed as a reference to the original object itself?

Yes, pretty much. In JavaScript, anything that's not a primitive type (number, boolean, string) is a reference type. If you pass an object into a function, you are passing a reference to the original object. If that object is modified inside a function, the original object is modified.

In other words, this has nothing to do with variable scope but rather with what the variables are actually referring to.