How to create javascript variable with other variable value in name

Question

Hi I need to create a load of variables in a javascript loop so say my loop goes round 5 times starting at 0 by the end of it the following variables should be defined:

variable_0
variable_1
variable_2
variable_3
variable_4

Can anyone tell me how to do this please?

Use an object or array for grouping stuff please :X also possible duplicate of [Javascript dynamic variable name](http://stackoverflow.com/q/5117127/995876) — Esailija, Jun 29 '12 at 10:10
possible duplicate of [JavaScript: Get local variable dynamicly by name string](http://stackoverflow.com/questions/1920867/javascript-get-local-variable-dynamicly-by-name-string) — Florian Margaine, Jun 29 '12 at 10:15

Ja͢ck · Accepted Answer · 2012-06-29T10:20:32.150

4

This will create "global" variables by registering them on the window object:

for (var i = 0; i != 5; ++i) {
    window['variable_' + i] = null;
}

It's not really nice to do that though =/ a better way is to define an object in which you create dynamic properties.

var obj = {}
for (var i = 0; i != 5; ++i) {
    obj['variable_' + i] = null;
}

console.log(obj.variable_0); // null

edited Jun 29 '12 at 10:20

answered Jun 29 '12 at 10:06

Ja͢ck

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score 1 · Answer 2 · answered Jun 29 '12 at 10:07

1

Why not just use an array:

var variable = [];

If you really want to create 5 variables, you need to choose the scope of them, the easiest is probably window, then you can use the sqare bracket syntax:

for(var i=0;i<5; i++){
    window["variable_" + i] = 0; // or anything really!
}

Now the following variable is available:

window.variable_1 = 123

answered Jun 29 '12 at 10:07

Jamiec

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you can use the square bracket syntax on _any_ object. – Alnitak Jun 29 '12 at 10:31
@Alnitak - I didnt say you couldn't! I just used `window` as the example. – Jamiec Jun 29 '12 at 10:53

Alnitak · Answer 3 · 2012-06-29T10:14:06.727

You can only create variably named variables as part of an Object:

obj['variable_' + i] = value;

There's no equivalent for function scoped variables, although you can of course do:

function foo() {
    var obj = {};
    for (var i = 0; ... ) {
        obj['variable_' + i] = value;
    }
}

You can fake global variables (but shouldn't) by using the window global object in place of obj, as shown by @Jack.

Of course in most circumstances (and since you're using numbers to differentiate the variables) what you should really do is use an array:

var myvar = [];
for (var i = 0; i < n; ++i) {
    myvar[i] = ...;
}

How to create javascript variable with other variable value in name

3 Answers3