Primitive vs Reference Value in JavaScript

Understanding Primitive Values:

Unlike the book's suggestion, primitive values are indeed stored in memory. They occupy small amounts of space and can hold simple information like numbers, booleans, null, and undefined.

Concept of Reference Values:

Reference values, on the other hand, are not directly stored as values. Instead, they contain the address or location of the actual object in memory. This allows multiple reference values to refer to the same object.

Example:

Consider the code snippet:

var foo = 123;

In this case, the variable foo is assigned a primitive value, 123. It occupies a small portion of memory and stores the actual value itself.

Passing Values in JavaScript:

When passing primitive values, they are passed by value. This means a copy of the actual value is created and passed to the function.

When passing reference values, they are passed by reference. This allows the function to access the original object stored in memory.

Comparison of Reference Values:

Two reference values are considered equal if they refer to the same object in memory, even if they contain different sticky notes (descriptions).

Important Note:

JavaScript is a dynamic language, meaning that variables can hold different data types at different times. This also applies to the primitive and reference values, as they are all internally allocated from the heap memory.