Objects within Objects in JavaScript

Question

I am trying to setup a constants file for one of my sites. I am trying to set it up so I can get string constants when needed.

What I have so far (Not working, kind of C# ish)

var Constants = new SiteConstants();

function SiteConstants()
{
    this.Training = function Training()
    {
        this.Staff = function Staff()
        {
            this.fetch = "someurl";
        }
    }
}

console.log(Constants.Training().Staff().fetch); //Fail - what i want to call
//or something similar like Constants.Training.Staff.fetch
console.log((new Constants.Staff()).fetch); //Success

Is this possible in JavaScript, and if not, can someone suggest an alternative?

since they are constructors, (new (new Constants.Training()).Staff()).fetch — user1375096
– user1375096, Commented Jul 24, 2014 at 1:28
Constants per se do not exist in Javascript. If you are trying to create objects in other objects, just use object literal notation and assignment as appropriate. — Kelstar
– Kelstar, Commented Jul 24, 2014 at 1:29
@K.Hallman While you are right, there is the const keyword (developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…) but I wouldn't suggest it since it isn't widely supported yet. And I think it's pretty obvious what the OP means by "constants", and object literals, as you suggest, are probably the best way to go... — Ian
– Ian, Commented Jul 24, 2014 at 1:30
@Ian const is a reserved word but not presently implemented in the ECMAScript spec, to my knowledge. The OP was confusing because it used a word that has a specific meaning in an unclear way. — Kelstar
– Kelstar, Commented Jul 30, 2014 at 18:57

Anton L · Accepted Answer · 2014-07-24 01:28:46Z

4

You have to use objects instead of functions for this purpose.

var Constants = {
    Training: {
        Staff: {
            fetch: "someurl"
        }
    }
};

answered Jul 24, 2014 at 1:28

Anton L

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Comments

royhowie · Accepted Answer · 2014-07-24 01:31:19Z

2

I would suggest an entirely different approach; one that is more idiomatic to JavaScript: JSON.

{
    "siteConstants" : {
        "training" : {
            "staff" : {
                "fetch" : "someurl"
            }
        } 
    }
}

Then, if you have this object attached to var constantsObject, you can access the constants as such:

constantsObject.siteConstants.training.staff.fetch;    // returns "someurl"
constantsObject["siteConstants"]["training"]["staff"]["fetch"] // returns "someurl"

answered Jul 24, 2014 at 1:31

royhowie

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4 Comments

Ian Over a year ago

There's no "JSON" type in JavaScript. You're creating an object literal, which another answer has already provided

royhowie Over a year ago

@Ian I never called it a type. I said "approach."

Ian Over a year ago

I still don't see why JSON should even be referenced here. JSON is a data transfer format, and has nothing to do with JavaScript (other than the fact that it was derived from JS objects)

royhowie Over a year ago

@Ian Also, I hadn't seen Anton L's answer until after I had posted mine. Regardless, JSON could be used externally, which would probably serve the OP's request better: "I am trying to setup a constants file for one of my sites."

Kyle Emmanuel · Accepted Answer · 2014-07-24 01:40:10Z

2

Try to define each constructor properly.

function SiteConstants()
{
  this.training = new Training();
}

function Training()
{
  this.staff = new Staff();
}

function Staff()
{
  this.fetch = "someurl";
}

Or you can also do it like this:

function SiteConstants()
{
    function Training()
    {
        function Staff()
        {
            this.fetch = "someurl";
        }

        this.Staff = new Staff();
    }

    this.Training = new Training();
}

edited Jul 24, 2014 at 1:40

answered Jul 24, 2014 at 1:30

Kyle Emmanuel

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1 Comment

JosephGarrone Over a year ago

I needed to have them enclosed, so that there would be no conflicting objects (We have a ton of javascript objects on our site)

ioseph · Accepted Answer · 2014-07-24 01:26:41Z

1

You are defining Training as a constructor but never actually invoking it. What you want is:

function SiteConstants()
{
    var Training = function Training() //constructor
    {
        this.Staff = function Staff()
        {
            this.fetch = "someurl";
        }
    }
    this.Training = new Training();
}

And so on for the inner class.

answered Jul 24, 2014 at 1:26

ioseph

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Comments

Khalid · Accepted Answer · 2014-07-24 01:30:48Z

1

you need to create a new object like this

var Obj = new Constants.Training();

then you need to call the function Staff and console.log the Obj.fetch

Obj.Staff();
console.log(Obj.fetch);

or you can do this

function SiteConstants()
{
    this.Training = function Training()
    {
        this.Staff = function Staff()
        {
            this.fetch = "someurl";
        }
    }
}
var Constants = new SiteConstants();
Constants.Training = new Constants.Training();
Constants.Training.Staff();
console.log(Constants.Training.fetch);

answered Jul 24, 2014 at 1:30

Khalid

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