Objects are always passed by reference.

If you assign a variable the same value of another, if it’s a primitive type like a number or a string, they are passed 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 also arrays and functions are objects, so they are passed by reference, too.

Lessons in this unit: