Originally published at: http://www.sitepoint.com/immutability-javascript/
Immutability is a core principle in functional programming, and has lots to offer to object-oriented programs as well. In this article, I will show what exactly immutability is all about, how to use this concept in JavaScript, and why it’s useful.
What is Immutability?
The text-book definition of mutability is liable or subject to change or alteration. In programming, we use the word to mean objects whose state is allowed to change over time. An immutable value is the exact opposite – after it has been created, it can never change.
If this seems strange, allow me to remind you that many of the values we use all the time are in fact immutable.
Continue reading this article on SitePoint