custom javascript objects as properties of other custom javascript objects

Question

I want to create some custom javascript objects some of which have properties which are other objects. I'm not sure what the syntax would be to do this. My pseudo code is below with the idea that I have a person object and an order object. The order object has a property that I want to be of the person object type. Is this possible in javascript and if so, can someone give me a basic example? Thanks.

var person {
    name: "John",
    gender: "M",
    age: 3  
}

var order {
    customer: person, /*the property name is customer but of type person - is this possible?*/
    total: 100  
}

Šime Vidas · Accepted Answer · 2012-01-25 16:23:09Z

3

Consider constructors:

function Person( name, gender, age ) {
    this.name = name;
    this.gender = gender;
    this.age = age;
}

function Order( customer, total ) {
    this.customer = customer;
    this.total = total;
}

Usage:

var person1 = new Person( 'John', 'M', 3 );
var order1 = new Order( person1, 100 );

The constructors act as classes. You invoke them via new to create new instances (persons and orders).

answered Jan 25, 2012 at 16:23

Šime Vidas

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4 Comments

pleasedontbelong Over a year ago

+1 for the O.O. solution... but if I may, I'd suggest to use a framework (like Mootools) instead of using the native JS O.O., basically is the same but it save you the headache of having complex types as attributes. In this example, if you do person1.age = 5; you'd also change the order1 variable and it might cause you some troubles later if you're not careful

Šime Vidas Over a year ago

@pleasedontbelong It doesn't change the order1 object. This object has a customer property which is a reference to the person associated with the order. A specific person (e.g. 'John' in this example) is represented by exactly one object. All orders made by that person have a reference to that object. I'm not sure how this design pattern could lead to problems later on.

pleasedontbelong Over a year ago

=P srry i was thinking about this copypastecode.com/165660 but in this example they set the properties directly in the prototype and not in the constructor (like you did).. i forgot that this in the constructor points to the instance and doesn't affect the prototype

Šime Vidas Over a year ago

@pleasedontbelong That's why you generally want to only have functions in the prototype (the instance methods which are shared by all instances). Instance-specific information is assigned to the instance directly or bound to its privileged methods through closure.

wheresrhys · Accepted Answer · 2012-01-25 16:19:48Z

1

You were almost correct; all you need is to include some '='

var person = {
    name: "John",
    gender: "M",
    age: 3  
}

var order = {
    customer: person, /*the property name is customer but of type person - is this possible?*/
    total: 100  
}

answered Jan 25, 2012 at 16:19

wheresrhys

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Comments

David Hoerster · Accepted Answer · 2012-01-25 16:19:05Z

0

You could do this:

var person = {
    name: "John",
    gender: "M",
    age: 3  
};

var order = {
    customer: person,
    total: 100  
};

This also passes in JSLint. You were missing '=' signs.

answered Jan 25, 2012 at 16:19

David Hoerster

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Comments

Richard Dalton · Accepted Answer · 2012-01-25 16:20:54Z

0

You code is nearly fine (missing the = to assign the anonymous object to the variable):

var person = {
    name: "John",
    gender: "M",
    age: 3  
};

var order = {
    customer: person, /*the property name is customer but of type person - is this possible?*/
    total: 100  
};

http://jsfiddle.net/D7u3x/

answered Jan 25, 2012 at 16:20

Richard Dalton

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Comments

dsummersl · Accepted Answer · 2012-01-25 16:21:37Z

0

Sure, thats pretty much it. Your syntax is a little off, but only slightly.

Here is your example: jsfiddle

answered Jan 25, 2012 at 16:21

dsummersl

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