I tried a simple function to branch off to different functions depending on an argument, like a switch but indexed (and hopefully faster) and dynamic. I originally typed the first version in a single line in the debugging console. No need to tell me all the improvements it needs, this is not meant to be a production version. Here, I've just made…

confusing the interpreter.js

// First version:

var goto = function (where) {
    return {
        a: function () {
            console.log('a');
        },
        b: function () {
            console.log('b');
        }
    }[where]();
};
goto ('b');

// Without the return doesn't work:

var goto = function (where) {
    {
        a: function () {
            console.log('a');
        },
        b: function () {
            console.log('b');
        }
    }[where]();
};
goto ('b');