JavaScript consts Aren't Constants - JavaScript Quick Fix

Does JavaScript treat constant arrays and objects the same way as numbers, strings, and booleans? Turns out not. So let's see why that is and how, if you don't understand it, you can easily put bugs into your React applications.

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#javascript #quickFix

[frankkevy]

Every video I watch from this channel make me realize every time that I'm still walking in the dark
Thanks for today's light Jack👍🏾

[dgcp]

I was literally watching the creator of redux saying it really don't matter whether to use let or const bc const can be mutated too. And this popped up on my notifications, life is so weird sometimes.

[drewbird]

Just found you last week Jack. And I can't stop watching 👀

[seatube]

Jack, your videos are always awesome, thanks! Just wanted to quickly add that Object.freeze() will make object properties immutable at runtime (shallow freeze only). I don't see it used often because--as you mentioned--it's relatively inexpensive to create shallow clones of objects and pass references to them instead of the original. However, there are a few proposals to TC39 involving Object.freeze() under the hood (defensible classes/frozen prototypes, and a new proposed syntax for Object.freeze() and Object.seal()), so I thought it was worth mentioning :)

[chrislr]

This is a very clear explanation of an essential notion.

[AbdelhameedG]

Thanks Jack please keep this videos coming everyday, God bless you.

[Will_U]

Object.freeze can be also useful to make arrays and objects, well... truly constants.
But I still can't wait for Records and Tuples coming to JavaScript - they seem really nice.

[MrKeepItTrill]

THANK YOU for this video. Finally I understand _why_ we need to destructure objects when changing state. I sometimes wish JS syntax could be a bit more clear about what's a "real" value and what's just a memory location.

[prmming]

Interesting explanation, normally I use "readonly" keyword for objects and "const" for primitive in TS (with Angular)

[JBuchmann]

As others have said, object.freeze() helps here. But also if you use Typescript you can make your object or array readonly

[akashtakawale]

Primitive datatypes are passed by value and Non primitive data types are passed by reference.

[solowolf]

hey just had a doubt regarding the useState example, lets assume the useState is an array containing 10k objects. while updating state using setState, since we will need destructure the current state array of objects every time, this thing won't be performant enough. How can we oversome this issue @JackHerrington

[shubhamlatiyan]

Thanks, Jack for the awesome videos, Really appreciate it.

[darkmift]

There's always object.freeze if you really need to limit.

[JulioDx]

Thanks for the video, very informative.

[NilsLutz]

Hi Jack awesome session. I was wondering which tool you use for painting on your screen with a pen in that rainbow colors?

[captstrugglebunny]

I've been reading through the 2nd edition of You Don't Know JS, and in it, Kyle Simpson (the author) suggests to only use const for primitive values, while using let (or var) for all other values in order to alleviate some of this confusion. I was wondering what your thoughts on that stance are?

[PhilipAlexanderHassialis]

Ah, the eternal pain of stack and heap, where naive dreams of value equality go to die :S

[shreyas.jadhav]

Great video! Also should we actually spread the previous state which is passed in first param as setState is async? Like setState(prev => ({ …prev, name: “nee”})

[aleksd]

Doesn’t Object.freeze also kind of help?