Practice: Immutable vs. Mutable in JavaScript

Understanding the concept of mutable and immutable in JavaScript is vital to prevent programming errors. For example, we know that numbers are immutable. This article presents examples that you can try to understand this concept. This exercise does not count towards your grade. It is just for practice!

Primitive

In JavaScript, a primitive (primitive value, primitive data type) is data that is not an object and has no methods. There are 7 primitive data types: string, number, bigint, boolean, undefined, symbol, and null.

Most of the time, a primitive value is represented directly at the lowest level of the language implementation.

All primitives are immutable, i.e., they cannot be altered. 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.

Source: Mozilla, https://developer.mozilla.org/en-US/docs/Glossary/Primitive
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