How to access variable dynamically inside an anonymous function/closure?

Question

To keep the global namespace clean, my JavaScript code is wrapped like this:

(function() {
    /* my code */
})();

Now I have some variables declared in this scope which I want to access using a variable variable name (e.g. the name is 'something' + someVar). In the global scope I'd simply use window['varname'], but obviously that doesn't work.

Is there a good way to do what I want? If not I could simply put those variables inside an object to use the array notation...

Note: eval('varname') is not an acceptable solution. So please don't suggest that.

Could you say more specifically what it is you want to do when you want to "access them dynamically"? Do you want to access them outside the function? That's not possible AFAIK. — joriki
– joriki, Commented Feb 5, 2011 at 13:50
No, i just want to access them without hardcoding the variable name - but from inside my function. — ThiefMaster
– ThiefMaster, Commented Feb 5, 2011 at 13:51
With "dynamically" i mean with a dynamically generated variable name. — ThiefMaster
– ThiefMaster, Commented Feb 5, 2011 at 13:56

mVChr · Accepted Answer · 2011-02-05 14:34:35Z

8

This is a good question because this doesn't point to the anonymous function, otherwise you would obviously just use this['something'+someVar]. Even using the deprecated arguments.callee doesn't work here because the internal variables aren't properties of the function. I think you will have to do exactly what you described by creating either a holder object...

(function() {
  var holder = { something1: 'one', something2: 2, something3: 'three' };

  for (var i = 1; i <= 3; i++) {
    console.log(holder['something'+i]);
  }
})();

answered Feb 5, 2011 at 14:34

mVChr

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Comments

yuxhuang · Accepted Answer · 2011-02-05 14:24:54Z

2

(function(globals) {
    /* do something */
    globals[varname] = yourvar;
})(yourglobals);

edited Feb 5, 2011 at 14:24

answered Feb 5, 2011 at 13:52

yuxhuang

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3 Comments

ThiefMaster Over a year ago

"To keep the global namespace clean" - so obviously I do not want to add it to the global namespace.

casablanca Over a year ago

@ThiefMaster: globals doesn't necessarily mean global namespace -- it's just a parameter here and could very well be your own namespace. This doesn't deserve a -1.

ThiefMaster Over a year ago

The initial answer only suggested window[varname] = yourvar;

hugomg · Accepted Answer · 2011-02-05 14:53:44Z

1

evil solution/hack: Put the variable you need in a helper object obj and avoid having to change current uses to dot notation by using use with(obj){ your current code... }

edited Feb 5, 2011 at 14:53

answered Feb 5, 2011 at 14:47

hugomg

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1 Comment

gion_13 Over a year ago

it should be avoided... it's a bit slower

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