Question

I’m trying to reuse a complicated function, and it would work perfectly if I could change the value of a local variable that’s inside a conditional inside that function.

To boil it down:

var func = complicated_function() {
    // lots of code
    if (something) {
        var localvar = 35;
    }
    // lots of code
}

I need localvar to be some other number.

Is there any way to assign localvar to something else, without actually modify anything in the function itself?

Update: The answer is yes! See my response below.

Answer 1

I asked this question about three weeks ago and within a half hour got five answers that all basically told me it wasn’t possible.

But I’m pleased to announce that the answer is YES, it can be done!

Here’s how:

var newfunc = func.toString().replace('35', '42');
eval('newfunc = ' + newfunc);
newfunc();

Of course, it uses eval, which probably means that it’s evil, or at least very inadvisable, but in this particular case, it works.