Value Types vs Reference Types

• Primitives or value types are copied by their value
• Reference types or objects, are copied by their reference.

Values Types

• In value types, the value is stored inside of this variable.
• When you copy, value that is stored in the variable is copied into this new variable. Example 1

let x = 10;
let y = x;
x = 20;

Example 2

let x = 10;
function change(param) {
	param = 30;
}
change(x);

Reference Types

• In reference types, the object is stored somewhere in the memory, and the address of that memory location is stored inside the variable
• When you copy, the address or the reference that is copied

Example 1

let x = {value: 10};
let y = x;
x.value = 20;

Example 2

let x = {value: 10};
function change(param) {
	param.value = 30;
}
change(x);