How to check if a directive or controller is available in a module using Angularjs

Question

In angularjs, given a module, how do you check if a directive/controller exists given a module.

I have a module and I want to know if some particular directives have bee

Answer 1

    var controllers = [];

    _.each(app._invokeQueue, function(value, index) {
        if (value[0] !== '$controllerProvider') {
            return;
        }

        controllers.push(value[2][0]);
    });

    if (controllers.indexOf('controller-i-want') === - 1) {
        // controller is undefined
    }