Passing objects to functions.If you pass an object (i.e. a non-primitive value, such as Array or a user-defined object) as a parameter, and the function changes the object's properties, that change is visible outside the function, as shown in the following example:

objects-as-parameter.js

var myFunc;
var num = 0;
if (num === 0){
  myFunc = function(theObject) {
    theObject.make = "Toyota";
    theObject.year = "2003";
    return theObject;
  };
}

var mycar = {make:"Honda", year:"1993"};

console.log(mycar);
myFunc(mycar);
console.log(mycar);