CODEWITHSUNDEEP
javascriptnode.js
PositiveGuy
PositiveGuy

Reputation: 20262

Adding properties dynamically to node module

I am experimenting with different ways to code a Node.js module and tried this:

game.js

    var board = require('./board'),
        player = require('./player');

    // setting module.exports to a function constructor so I can make instances of this node module from my test
    var game = module.exports = function(){};

    // dynamically add properties and set their default values
    // I don't think I need to use any prototypes here right?
    // And yes I realize I could use ES6 classes with an explicit constructor but that's a suggestion we can put on the side for now...
    game.initialize = function(){
        game.started = false;
        game.status = 'not started';
        game.board = board.create();

        return game;
    };

    game.start = function(){
        game.started = true
    };

game-test.js

let chai = require('chai'),
    should = chai.should(),
    game = require('../src/game');

describe('Game - Initial State', () => {
    var newGame;

    beforeEach((done) => {
        newGame = new game().initialize;
        done();
    });

    it('should contain a new board to play on', () => {
        should.exist(newGame.board);
    });
...

I'm getting the error "Cannot read property 'board' of undefined"

If I remove the .initialize() I get an instance of game but then no properties. I'm not sure if this is even a good pattern but first would like to know what I'm doing wrong here. And then any additional suggestions I'm open to hearing.

Upvotes: 1

Views: 509

Answers (1)

Cyrbil
Cyrbil

Reputation: 6478

Game.initialize is a function.

In your test your are not calling the function, so your variable newGame is just a ref to Game.initialize instead of a Game instance

// your line
newGame = new game().initialize;
// should be
newGame = new game().initialize();

Edit: Also, you may want to use this instead of game in your initialize() function.

Upvotes: 4

Related Questions