javascript pass by reference

function add(a, b, output) {
  output.out = a + b;
}

var output = {};
add(5, 3, output);
console.log(output); //output: {out: 8}function func(obj) {
  obj = JSON.parse(JSON.stringify(obj)); //If too slow, replace with other method of deep cloning
  obj.a += 10;
  return obj.a;
}

var myObj = {a: 5};
func(myObj); //Returns 15 and myObj.a is still 5