Create multiple variables inside for loop

Question

I am trying to create multiple new variables inside a loop. The number of new variables depends on the lenght of another variable (variable "list" used below).

for(var i = 0; i < list.lenght; i++) 
{ 
var counter + i;   // create new variable (i.e. counter1, counter2,...)
}

I found a lot of very simmilar questions on StackOverflow, and the answer is mostly using an array (i.e. How do I create dynamic variable names inside a loop?).

If I use the suggested solution, do I create an array of variables? So in my case I will create multiple counters and I can then add values to that variables, i.e.:

counter6++;

If that is not the case how could I tackle the problem?

I apologize for asking you to explain an old answer, but I cannot comment in the old one because of low reputation.

Should the dynamically created variable be assigned a value? — guest271314
– guest271314, Commented Mar 11, 2017 at 18:54
what would you do with the new created variables? how would you address them? — Nina Scholz
– Nina Scholz, Commented Mar 11, 2017 at 18:55
You don't create an "array of variables". You create an array of values, exactly as shown in the answers in the dupe. — georg
– georg, Commented Mar 11, 2017 at 18:58
@user2375263: yep, and instead of counter6++ you'll write counter[6]++ — georg
– georg, Commented Mar 11, 2017 at 18:59

pery mimon · Accepted Answer · 2017-03-19 10:58:57Z

3

You have some options here :

Create them global (not best practice ) :

for(var i = 0; i < list.lenght; i++){ 
  window['counter' + i] = 0;   // create counter1, counter2,...)
}

Use object :

var scope = {};
for(var i = 0; i < list.lenght; i++){ 
  scope['counter' + i] = 0;   // create scope.counter1, scope.counter2,...)
}

Use Object with with keyword

var scope = {};
for(var i = 0; i < list.lenght; i++){ 
  scope['counter' + i] = 0;   // create scope.counter1, scope.counter2,...)
}
with(scope){
 // here you can acesess keys in the scope object like them variable on the function scope
 counter0++
}

Use plain old Array

var scope = new Array(list.length);

edited Mar 19, 2017 at 10:58

answered Mar 11, 2017 at 19:08

pery mimon

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guest271314 · Accepted Answer · 2017-03-11 19:09:46Z

You can create an object, set property names to expected variable names, then use object destructuring assignment to get the property assignment or index of an object having a .length as a variable identifier; or use array destructuring to assign an identifier to a specfic index.

let [list, obj] = ["abc", {}];

for (let i = 0; i < list.length; i++) {
  obj["counter" + i] = list[i]
}

let {counter0, counter1, counter2} = obj;

console.log(counter0, counter1, counter2);

Alternatively

let list  = "abc";

let {0:counter0, 1:counter1, 2:counter2} = list;

console.log(counter0, counter1, counter2);

let list  = ["a","b","c"];

let [counter0, counter1, counter2] = list;

console.log(counter0, counter1, counter2);

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