Object is not a function - Module with Param

Question

I'm trying to inject a gateway by using a node module. Not sure if I can do this because I get a 'object is not a function error' on the line var response = new controller(gateway).find();

or maybe I should be able to do this with a node moduile, but not doing this right.??

Note: Although the code in the controller is not using the gateway yet, I want to be able to inject it for now just to make sure I can.

someFile.js

var controller = require('someController');
var gateway = require('someGateway);

var response = new controller(gateway).find();

someGateway.js

'use strict';

module.exports = function(){
    var _data;

    return {
        data: function(someData){
            _data = someData;
        },
        find: function(){
            return _data;
        }
    };
}();

someController.js

'use strict';

module.exports = function(gateway){

    var _gateway = gateway;

    return {
        find: function(searchText){

            var response = {};

            if(typeof searchText === "undefined"){
                response.statusCode = 400;
            }

            return response;
        }
    };
}();

UPDATED:

I tried changing it to this:

someFile.js

var controller = require('someController');

var response = controller.find();

someControllerjs

'use strict';

var Controller = function(){

    var _find = function(searchText){
        var response = {};

        if(typeof searchText === "undefined"){
            response.statusCode = 400;
        }

        return response;
    };

    return {
        find: _find
    };

}();

module.exports = Controller;

I'm trying to go with the pattern this dude has but still I get the same error. http://rob.conery.io/2012/02/25/testing-your-model-with-mocha-mongo-and-nodejs/

Answer 1

I'm not 100% sure what it is exactly you're trying to achieve with this code, but maybe I can shed some light on what is going on :)

1. var gateway = require('someController');

You ask Node.js to load some module called 'someController'. It goes and finds someController.js and begins executing the file.

2. module.exports = function(gateway){ ... }();

This function is immediately invoked (being a IIFE) and whatever is returned from it is assigned to be the "output" of that module. In your function, you return a plain object with a find method.

In memory, controller now equals this object:

{
    find: function(searchText){

        var response = {};

        if(typeof searchText === "undefined"){
            response.statusCode = 400;
        }

        return response;
    }
};

3. var response = new controller(gateway).find();

You call new on the object above, and try to call it as a function. However, it is an object. You can't call controller(gateway) because controller is only equal to an object. Therefore, you get the error that you mentioned.

---

I think you may accidentally be trying to assign a function to module.exports, rather than an IIFE. Keep in mind that the brackets at the end of each of your modules (}();) is causing the function to execute immediately and set the result value to be the value of the module. Try removing the function call brackets at the end of your module and you should have better luck!