How to reference properties of current object in JS [duplicate]

Question

Possible Duplicate:
Self-references in object literal declarations

I have some simple objects in JS like this example:

var object = {
 firstname : 'john',
 lastname : 'paul',
 wholename : firstname + lastname
}

Well this simple thing doesn't work; john and paul are undefined in wholename, so I tried to use the 'this' operator which works ONLY if I do a function (getWholeName(){return this.firstname+this.lastname} ). But if I want to use a variable and not a function, how can I do? I also tried object.firstname + object.lastname but it doesn't work.

Stefan · Accepted Answer · 2012-12-25 22:38:33Z

14

There is no way to reference the object, but you can add the properties dynamically:

var object = { 
    firstname : 'john', 
    lastname : 'paul'
};

object.wholename = object.firstname + object.lastname;

EDIT:

And why not wrap it in a function?

var makePerson = function (firstname, lastname) {
    return {
        firstname: firstname,
        lastname: lastname,
        wholename: firstname + lastname  // refers to the parameters
    };
};

var object = makePerson('john', 'paul');

answered Dec 25, 2012 at 22:38

Stefan

4,2163 gold badges36 silver badges48 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Rayjax Over a year ago

Ok thank you. The why I am doing this is that I am trying to have a well organized code in a huge web app I am building ; and so I decided to regroup similar functions and variables in objects like this. Is this the right way of doing it ? I know about TypeScript and Modules but do I need to use TS to achieve something as simple as groups of functions/variables ?

Stefan Over a year ago

@user1397271 you can do this in plain JS: try introducing namespaces (like var MYAPP = { }; MYAPP.data = ...) and try breaking down big functions into smaller ones. Consider using the module pattern: adequatelygood.com/2010/3/JavaScript-Module-Pattern-In-Depth

Rayjax Over a year ago

when you say namespaces like var MYAPP = {}, it means it is the same as my example with var object = {}, so will I run into the problem I was asking about ?

Stefan Over a year ago

@user1397271 yes, it will if you need to reference the thing that you're defining at the same time. But libraries can help with that, i.e. github.com/fabiooshiro/namespace-js or elegantcode.com/2011/01/26/basic-javascript-part-8-namespaces

user1574041 · Accepted Answer · 2012-12-26 12:14:54Z

4

In Javascript, every function is an object. You should declare your Object's constructor as a function like this:

function person(firstname,lastname)
{
this.firstname=firstname;
this.lastname=lastname;

this.wholeName=wholeName;

 //this will work but is not recommended.
 function wholeName()
 {
 return this.firstname+this.lastname;
 }
}

you can add extra methods to your object by prototyping it aswell , which is the recommended way of doing things. More info here:

http://www.javascriptkit.com/javatutors/proto.shtml

edited Dec 26, 2012 at 12:14

answered Dec 25, 2012 at 22:45

user1574041

2574 silver badges16 bronze badges

3 Comments

charlietfl Over a year ago

if everything is a function...what's this => var obj={1:1,2:2}?

user1574041 Over a year ago

You are right, but every function is an object though. That's what i meant. I stand corrected :)

David G Over a year ago

Did you just rip this off of w3schools or some other website?

Collectives™ on Stack Overflow

How to reference properties of current object in JS [duplicate]

2 Answers 2

4 Comments

3 Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

4 Comments

3 Comments

Linked

Related