I am trying to create a bunch of variables like this:

function l(){
    var a1 = 2,
        a2 = 4,
        a3 = 6,
        a4 = 8,
          .
          .
        a20 = 40;
}

But this is taking too many lines, and I am searching for a way to do it smarter. This is what I have come up:

function l(){
    for(var i=0; i<20; i++){
        var ("a"+i) = 2*i;
    }
}

But it probably won't work, and if it works (it does not) the variables will still be inside the for scope. Any ideas?

window["a"+i] or eval(...)

These don't work because I don't want them to be in the global scope.

Usually an Array would be fine, but I am just experimenting if this is possible in JavaScript. Maybe in the future I would encounter something like this.

I am trying to create a bunch of variables like this:

function l(){
    var a1 = 2,
        a2 = 4,
        a3 = 6,
        a4 = 8,
          .
          .
        a20 = 40;
}

But this is taking too many lines, and I am searching for a way to do it smarter. This is what I have come up:

function l(){
    for(var i=0; i<20; i++){
        var ("a"+i) = 2*i;
    }
}

But it probably won't work, and if it works (it does not) the variables will still be inside the for scope. Any ideas?

window["a"+i] or eval(...)

These don't work because I don't want them to be in the global scope.

Usually an Array would be fine, but I am just experimenting if this is possible in JavaScript. Maybe in the future I would encounter something like this.

• javascript

• 1 Just a note: they will not be in the for scope--everything in JavaScript is function scoped. – JoshRagem Commented Dec 9, 2012 at 6:54
• 1 i would suggest using an array – Justin McDonald Commented Dec 9, 2012 at 6:55
• If you really don't want to use an array for whatever reason, and you dont want to use window because of global scope, just replace window with some other var... – Krease Commented Dec 9, 2012 at 6:58
• 1 @Derek they are only scoped within the for statement if you use let instead of var. But let is part of ES6. It's in Firefox now, though. But Josh is right, they are function scoped, not block-scoped because you used var. – Ray Toal Commented Dec 9, 2012 at 6:59

3 Answers 3

Don't do this. Do. Not. Do. This. Use an array.

Given the trouble you're having creating them programmatically, how do you think you'd refer to them programmatically?

I guess its better for you to go with an array, like:

function l(){
    var a = [];
    for(var i=0; i<20; i++){
        a[i] = 2*i;
    }
}

Or if you really want the long list of variables, try this. But its using eval()

function l(){
    var js = '';
    for(var i=0; i<20; i++){
        js += 'var a'+i+' = '+2*i+';'
    }
    eval (js);
}

As a matter of fact, I think using a object is a good idea.

var scope = {}
for (var i=1;i<=20;i++) {
  scope['a'+i] = 'stuff';   
}

The result will be you have a scope object that contain every newly create variable you want!