JavaScript - declare variable with for loop item

Question

Is it possible to declare a variable differently for each iteration? Here is the general idea:

var userIds = [9110252, 55829847, 145189041]

    for(u = 0; u < userIds.length; u++){

        console.log(userIds[u]);

        var user+userIds[u] = userIds[u]; 
}

The question is why? You already have the values in an array, why would you need dynamic variable names. — adeneo, May 08 '16 at 09:27
This is a simplification of where I am actually using localStorage, as you have to declare a variable each time to get the stored item? e.g. `var user = localStorage.getItem('user');` — mellows, May 08 '16 at 09:32
Then you should tell us that, as with localStorage it would be completely different, all you'd do is `window.localStorage.setItem(user+userIds[u], userIds[u] )` and `localStorage.getItem(user+userIds[u]);`, no need for dynamic variable names — adeneo, May 08 '16 at 09:36

score 1 · Answer 1 · answered May 08 '16 at 09:34

1

It's not possible. But you also don't need that:

You won't be generating dynamic variable names, but you can have a different variable in each iteration of the for loop:

var userIds = [9110252, 55829847, 145189041]
for(u = 0; u < userIds.length; u++){
   console.log(userIds[u]);
   var user = userIds[u]; 
}

On the first iteration, user will hold 9110252, on the second a new value is set to variable user: 55829847 and so forth.

But in this case, as @adeneo mentioned: You already have: userIds[u] to refer to the value.

answered May 08 '16 at 09:34

Bruno Garcia

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Are you 100% certain it's not possible at all? Might there be a hack to do it? – Peter David Carter May 08 '16 at 09:39
It's not possible. I'm happy at least this 'feature' was not added to JS :) – Bruno Garcia May 08 '16 at 09:42
Can you prove it's not possible? If you can I'll more than happily upvote the answer... You might be able to prove the feature wasn't intentionally added to Javascript, but that's not quite the same thing... – Peter David Carter May 08 '16 at 09:43
can you prove it is? http://stackoverflow.com/questions/5117127/use-dynamic-variable-names-in-javascript – Bruno Garcia May 08 '16 at 09:44
I never said I could. You stated directly that it isn't. I took no such position. – Peter David Carter May 08 '16 at 09:45
Me, or the poster who just said it is possible in the new Javascript engine before someone deleted the comment? – Peter David Carter May 08 '16 at 09:52
@adeneo. He deleted it I guess.. Since that was nonsense. Maybe you can remove the downvote too :) – Bruno Garcia May 08 '16 at 09:54
You directly stated a position you cannot support. The downvote stays unless you can logically demonstrate the impossibility. I'm sorry if that seems harsh, but it is fair. – Peter David Carter May 08 '16 at 09:58
Here you go (if it's not part of the spec, it's not supported): https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Statements/var – Bruno Garcia May 08 '16 at 10:00
So your question is inaccurate as phrased, Bruno. Do you have a reason for leaving it as 'impossible' rather than 'not supported'? Perhaps you wish me to suggest an edit for you myself? As it is it may be misleading to new users and discourage creativity... – Peter David Carter May 08 '16 at 10:29
OP: Is it possible. The answer is: It's not. – Bruno Garcia May 08 '16 at 10:48
Then prove it. You've shown it's not supported according to a particular reference document, which is a different thing. – Peter David Carter May 08 '16 at 10:49

score 1 · Answer 2 · answered May 08 '16 at 09:36

1

We have arrays for that .Why do u need to have different name of variable when one array variable can do it for u and also it makes code easy to manage.

answered May 08 '16 at 09:36

Abhishek Panjabi

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DevNebulae · Answer 3 · 2016-05-08T11:04:41.203

Reading through the comments on the question and wanting to store it inside local storage. I would do this:

var userIds = [9110252, 55829847, 145189041];

for (var i = 0; i < userIds.length; i++) {
    var userId = 'user' + userIds[i];
    window.localStorage.setItem(userId, userIds[i]);
}

I would recommend however to reconsider this type of storage, because you're now storing redundant data. It's only distinguished with the word "user" in front of it.

User @Abhishek Panjabi also mentioned that this is the reason why we have arrays. He is correct in saying this.

Credits to user @adeno for his comment.

JavaScript - declare variable with for loop item

3 Answers3