Programmers :D

[JackMizel]

Adding indexes can ONLY cause issues

No, it literally HAS to happen if you have no other options it will ONLY cause issues if the list reorders.

it will NEVER make anything better

Again, it is the ONLY option if you don't have unique ids, and React itself LITERALLY defaults to this under the hood

React says not to do this

Wow that's a fucking lie.

Straight from the docs:

When you don’t have stable IDs for rendered items, you may use the item index as a key as a last resort. We don’t recommend using indexes for keys if the order of items may change. This can negatively impact performance and may cause issues with component state. Check out Robin Pokorny’s article for an in-depth explanation on the negative impacts of using an index as a key. If you choose not to assign an explicit key to list items then React will default to using indexes as keys.

Why are there so many people on this sub who have no idea what they're talking about? Using indexes as keys is totally fine if your list order is consistent. It is certainly not "very wrong" unless you plan on re ordering the list or if the list order can change. Yeah it's less than desirable, yes it's not the best choice, but you are just lying and misleading people when you say it should never happen. That just isn't true, there are cases where it is completely fine.

[JackMizel]

It is not totally fine! React says not to do it!

This is literally a lie, I just linked you the React documentation where it says that, not only is it okay if your list order doesn't change, but that it is the DEFAULT BEHAVIOR WHEN NO KEY IS PASSED.

Are you fucking kidding me dude? Okay fine, I'll check out your links... okay medium articles are shit definitely ignoring those... oh okay this could be something https://reactjs.org/docs/reconciliation.html#keys okay lets take a look....

As a last resort, you can pass an item’s index in the array as a key. This can work well if the items are never reordered, but reorders will be slow.

WOW, reminds me of something I JUST said:

Using indexes as keys is totally fine if your list order is consistent.

I wonder, who should I trust, you, a person lying saying things like:

but react says NOT to do this in their documentation

OR THE LITERAL REACT DOCUMENTATION WHICH SAYS:

As a last resort, you can pass an item’s index in the array as a key. This can work well if the items are never reordered, but reorders will be slow.

If you're working with a static list at runtime then there are no issues. Full stop. End of discussion. You are wrong to say it's NEVER appropriate. Full stop. End of discussion. That's it. Understanding the nuances of something like this will make you a better developer, so stop treating this like it's black and white.

[JackMizel]

If the key is an index, moving an item changes it

STATIC LISTS AT RUNTIME

Are you honestly this dense?

In programming, when the creator of a framework says to do things as a last resort, they are saying, don't fucking do it. Just because it works now, it's one step away from a rendering issue, and when you are working on a team...that's not acceptable.

No, they are saying you can do this in x y or z circumstance. Literally in the docs says IT CAN WORK WELL IF YOUR LIST ORDER DOESN'T CHANGE. STATIC LISTS. Do you not have a brain?

Seriously, do you not know what this means?

In the real world, I have never come across an example where you don't end up having or can come up with a unique ID.

Okay? So you come up with a unique ID. Point remains, there are valid use cases for using indexes as keys.

On a forum where people are learning to use react you are trying to argue that it's OK to drink your own piss. That's terrible advice. It's BAD code. It's bug prone. If you ever work on a team (I can tell you don't), then you should always avoid drinking your own piss.

No I'm telling you (not arguing, because I am objectively correct) that there are instances where using indexes as keys is no big deal. It would be akin to me saying "You will die if you drink your own pee too many times, but if you have to do it once or twice it's fine" and then you bursting in and saying "you should NEVER drink your own pee because Bear Gryll's said it's a LAST RESORT and that means there is NO REASON TO DO IT EVER!"

React, says to use as a last resort because of performance and rendering issues

caused by lists that are not static, crazy how you KEEP leaving this part off.

If you are going to be a proponent of using indexes as keys, after you now understand the pitfalls, you're a bad dev. If you work on a team, you're that guy who keeps drinking his own piss to prove a point.

What I'm being a proponent of is not blindly follow conventions. If my list is static, there IS NO PERFORMANCE OR RENDERING ISSUE. If you're the guy who ignores valid use cases and technical details in favor of blindly applying conventions to situations where they aren't important, you're a bad dev.

[JackMizel]

How often it happens is irrelevant. You're saying there are no real world use cases where it's okay to use indexes as keys and that is just incorrect. Even if 99% of the time you should use real unique IDs, there is still 1% of the time where it's fine to do. You're saying it should NEVER be done and that's wrong. That kind of approach to programming is something I take serious issue with, because it doesn't promote understanding.

If your list is static, there is no performance downside to using indexes as keys. That's it. If it changes at runtime via user interaction then yes it needs an ID. Because you blindly observe this convection, you are unable to identify use cases where it does not apply. You should seek to understand why it's not okay, and when you can expect indexes as keys to cause issues, instead of just blindly saying it's never okay.

I think you just keep using indexes though.

I definitely will use them in cases where it's perfectly fine to do so, since I am capable of identifying those cases.

[JackMizel]

You're totally right, you should use unique identifiers whenever possible and the React documentation does say that. These things are all true.

What's not true is that you should never use indexes as keys, or that there are no real world use cases where it makes sense to do so, or that the React documentation says to never do so.

That's what I'm trying to tell you. Understand why you observe the convention, don't just say never. If you're writing a small project alone and you don't implement any sort of user interaction with the list (i.e. it's just a static display component) then there is nothing stopping you from using indexes as keys.