accessing object property from function within same object

Question

accessing object property from function within same object

What I'm trying to do here is access the context property (or context.settings, more specifically) from within the ready function in the same object. I'm not sure what the correct syntax is to do this.

here's the code:

module.exports = {
    context: {
        settings: require('./settings')
    },
    listen: function(callback) {
      listen(context.settings.http.port);
      callback(null);
    },
    ready: function (err) {
      if (err)
      {
        throw err;
      }
      console.log("Ready and listening at http://localhost:" + context.settings.http.port);
    }
};

just for clarification, I'm referring to the line console.log("Ready and listening at http://localhost:" + context.settings.http.port);

Edit: a bit more context (ha)

I did try this.context.settings.http.port, but I get TypeError: Cannot read property 'settings' of undefined.

Here's the contents of settings.js, just to be sure...

module.exports = { 
  db: {
    host: '127.0.0.1',
    port: 27017,
    name: 'jsblogdemo'
  },
  http: {
    port: 3000
  }
};

Thanks!

javascript
oop
node.js
express

Answer 1

Another possibility is this:

module.exports = (function() {
    var context = {
        settings: require('./settings')
    },
    listen = function(callback) {
      listen(context.settings.http.port);
      callback(null);
    },
    ready = function (err) {
      if (err)
      {
        throw err;
      }
      console.log("Ready and listening at http://localhost:" + 
                    context.settings.http.port);
    };

    return {
        // context: context, // needed?
        listen: listen,
        ready: ready
    };
}());

Then the functions have local access to the context object without any worries about how they're called. And the context object can be kept entirely private if you like.

Answer 2

If it's a single, static object, you could just do:

module.exports.context.settings

If you want a permanently bound this, use .bind().

module.exports = {
    context: {
        settings: require('./settings')
    }
}
module.exports.listen = function(callback) {
    listen(this.context.settings.http.port);
    callback(null);
}.bind(module.exports);

module.exports.ready = function (err) {
    if (err) {
        throw err;
    }
    console.log("Ready and listening at http://localhost:" + this.context.settings.http.port);
}.bind(module.exports);

Answer 3

As long as a method isn't being bound to another context by call or apply, this refers to the current object context. For instance, use:

console.log(this.context.settings.http.port);

To print the listening port.