Conditional creation of closures in JavaScript

Question

Say I have a function like this:

function wrap_function(fnInput)
{
    if (somecondition)
    {
        return function() { 

            // Simplified example, in reality doing more stuff in here
            fnInput.apply(this, arguments)

        }
    }
    else
    {
        return fnInput;
    }
}

I'm assuming that if somecondition is false this function won't create a closure and therefore won't have performance/memory impacts associated with closures.

Is this correct?

The "performance/memory impacts" of a closure in this case is absolutely minimal. If somecondition is true, the activation object created when wrap_function is called stays on the scope chain of the anonymous function, but might be optimised away since no use is made of it. fnInput might be a direct reference to the original (function?) object passed to wrap_function. In the worst case, there is only one extra lookup when resolving the identifier fnInput inside the anonymous function. — RobG
– RobG, Commented Aug 24, 2011 at 1:23

RobG · Accepted Answer · 2011-08-24 01:18:26Z

1

If somecondition is false a closure will not be created. You're using the loosely typed nature of javascript in your example

edited Aug 24, 2011 at 1:18

RobG

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answered Aug 24, 2011 at 0:39

Kevin Bowersox

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1 Comment

Brad Robinson Over a year ago

Thanks... that's what I thought, just needed to be sure.

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