Objects are always passed by reference.

When you assign a variable the value of another, primitive types (like numbers and strings) are copied by value:

Take this example:

let age = 36
let newAge = age

newAge = 37

console.log(age) //36

With primitive types, the copy is an entirely new entity. With objects instead, you copy a reference to the same object:

const car = {
  color: "blue",
}

const anotherCar = car
anotherCar.color = "yellow"
car.color //'yellow'

Remember that arrays and functions are also objects, so they are passed by reference too.

Lessons in this unit:

0:	Introduction
1:	How to create an object
2:	Object properties
3:	▶︎ Objects are passed by reference
4:	Methods
5:	Passing objects as function arguments or returning objects from a function
6:	Accessing a property of the object inside a method using `this`
7:	Object destructuring
8:	Cloning objects
9:	Sort an array of objects by a property value
10:	Merging two objects into one
11:	apply, call, bind