passByValueReference.md

Passing by value of reference in JavaScript

Depending on the type of variable passed as an argument in a function, JavaScript passes either by value or reference.

Passing by value.

If we are passing a primitive (string, boolean, number, null, undefined, symbol), JavaScript passes by value, which means changing the value of this variable inside the function does not affect the original variabled passed from outside.

function change(name){
  name = "Patrick"
  console.log(name)
}

var name = "Charlie"

console.log(name) // Charlie

change(name) // Patrick

console.log(name) // Charlie

Passing by reference.

When the variable passed in a function is an object or array, JavaScript passed by reference, which means modifying the array/object inside the function is going to change the value of the original variable passed in from outside.

function change(details){
  details.name = "Patrick"
  console.log(details.name) // Patrick
}

var details = {
  name: "Charlie"
}

console.log(details.name) // Charlie

change(details) // Patrick

console.log(details.name) // Patrick