Understanding Immutability in JavaScript

We often hear the terms: immutable and immutability. What do they mean and, as developers, why should we care?

In this video, we look at immutability of primitives, arrays, and objects with JavaScript examples. And we enumerate why immutability is important for programming.

*Links*

*Content*
00:00 Understanding Immutability in JavaScript
00:43 Primitives in JavaScript: Naturally Immutable
02:10 JavaScript Array are Mutable
03:55 Embracing Immutability with Arrays
05:52 Mutable Nature of JavaScript Objects
07:28 Immutability with Objects
08:15 Why Is Immutability Important?
09:00 Wrap up

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😊About Me
Hey! I'm Deborah Kurata
I'm a software developer and YouTube content creator. I speak at conferences such as VS Live and ng-conf. I write articles for freeCodeCamp. And I'm a Pluralsight author with courses in the top 10 most popular (out of 7,000+) over the past 5 years. For my work in support of software developers, I've been recognized with the Microsoft Most Valuable Professional (MVP) award, and I'm a Google Developer Expert (GDE).

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#javascript #immutability #mutability #immutabilityinJavaScript

[jawwadalam]

Detailed simple explanation of why immutability is important. Thank you 👍

[karlee]

The video is very informative. You should include a visual evidence of the primitive data type being immutable. Same thing with object and array. I like how you make the connection to the memory instead of the value itself. It helps explain what is going on behind the hood in JavaScript. If you can show an updated video with actual example that would be grateful.

[RsPippen]

perfect timing! i was just dealing with a bug related to this topic

[elyoaprogrammer]

So important topic explained by @DeborahKurata!!!

[Sinan]

Great video again, now i know why immutability is important. Thank you!

[AesSedai]

Nice, this was a really good explanation why immutability is important, thank you :)

[FuyadFuyad-nsqg]

very informative and well descriptive tutorial video. Hope you will give us more and more informative and well descriptive tutorials .❤

[MANAHILEJAZ-sz]

Thanks for your help, there's is a same concept of mutability and immutability in python also

[house_sparrow]

Thank you so much!! Very clear explanation❤❤

[farzadbahadorifar]

you explain really well, thank for that.

[JJOhns-fytl]

so glad i found your channel. thank you for your clear explanations. one question though: when creating a new object by using the spread operator and the original object contains an array, i would copy the reference of the array, wouldn't I? So maybe I should figure out a combination of using the spread operator to treat the object as immutable and the with() method for the array. Or am i on the total wrong track?

[ibmmsayskhiedr]

Thanks a million I think immutability now became a piece of cake Thanks @Deborah

[NawalFatima-em]

slice performs a shallow copy of the array and it can be modified in future, so i think it should come under the mutable column

[respostasimples]

doing god's work Kurata, thanks!

[mechanical_engineer_]

Hi Deborah, been following you since 2020, have watched all of your Angular courses on Plural sight, my request and I believe this is currently the hot topic: Next.js, pls make a series on this..

[GreenClearScenery]

Hi Deborah, in the video you give an example of primitives being immutable.
So the code

total = 42; // (1)
total += 10; // (2)

means that in (1), total is pointing at a memory with value 42. Then, in (2), total is pointing at a different memory address with value 52.

But how can we re-access the value 42 ?? (We don't know the memory address for this anymore ?)

[SolidWorksMastery-hrsg]

one question : i've read that dynamic arrays (which we use in javascript) create a new array in memory in case of adding new value which would exceed the length of the array, so does that mean that sometimes the address of the array change ?

[povdata]

How to get value of p variable by prev address x?