Understanding Primitives, Objects, and the JavaScript Engine: A Developer's Guide

In JavaScript, knowing how different data types are managed can significantly impact the performance and behavior of your applications. Let’s dive into the two main categories of data types: primitives and objects.

Primitives vs. Objects

• Primitives: These include types like Number, String, Boolean, Undefined, Null, Symbol, and BigInt. They are stored in the call stack and are immutable, meaning their value cannot be changed.
• Objects: Objects include more complex structures like object literals, arrays, and functions. Unlike primitives, objects are stored in the heap, and they are reference types, which means they can be modified.

How the JavaScript Engine Works

• Call Stack: This is where primitives are stored. Because they are simple and small, they are stored directly in the stack, which is a fast and limited space.
• Heap: Objects are stored in the heap, which is a larger, slower area of memory. The heap is used for dynamic memory allocation, and because objects can be large and complex, they are stored here.

Understanding these fundamental concepts helps you optimize memory usage and avoid common pitfalls such as unintended side effects when manipulating objects.

?? Note: It is important not to confuse a primitive itself with a variable assigned a primitive value. The variable may be reassigned a new value, but the existing value can not be changed in the ways that objects, arrays, and functions can be altered.