Question

in an existing implementation (can’t change the structure much), i’m trying to call a function which is nested inside another function:

function outer(innerFunction, obj) {

    //TODO: call innerFunction here, passing obj as first parameter

    function inner1(obj) {
        alert(obj.key);
    }
}
outer('inner1', {key:'value'});

jsfiddle is here: http://jsfiddle.net/tbyyw/

i’ve alreay thought about using eval(), but i don’t know how to pass an object – and they say ‘eval is evil’ 😉

another solution i’ve come up with is checking the innerFunction string, but this means i have to know which inner functions exist (besides, adding new functions would mean having to write extra checks then):

if(innerFunction == 'inner1') inner1(obj);

so is there another way without changing the overall implementation?

Answer 1

Without changing the overall structure eval appears to be the only option:

function outer(funcName, obj) {

    var func = eval(funcName);
    func(obj);

    function inner1(obj) {
        alert(obj.key);
    }
}

There’s nothing particularly “evil” about eval as long as you have full control over the code, but if you want, you can insert an additional security check:

if (funcName.match(/\W/))
    throw "invalid function name!";

var func = eval(funcName);

This will raise an exception if someone tries to pass anything else than a simple identifier, i.e. a function name.