How to create an Custom Object with a Custom Object?

Question

In Javascript how would I create a Custom Object that has a property this is another Custom Object. For Example.

function Product() {
    this.prop1 = 1;
    this.prop2 = 2;
}


function Work(values) {
    this.front = values.front || "default";
    this.back = values.back || "default";
    this.product =  Product;
}

var w = new Work();
alert(w.product.prop1); //no worky

Nick Craver · Accepted Answer · 2010-10-29 18:12:07Z

3

You need to create an instance of Product, like this:

function Product() {
    this.prop1 = 1;
    this.prop2 = 2;
}
function Work(values) {
    this.front = values && values.front || "default";
    this.back = values && values.back || "default";
    this.product = new Product();
}
var w = new Work();
alert(w.product.prop1); //1

The front and back changes are a separate issue, since values wasn't being passed in in your example, you'd get an undefined error. You can test the result here.

Here's an alternative way I'd personally use to define those defaults:

function Work(values) {
    values = values || { front: "default", back: "default" };
    this.front = values.front;
    this.back = values.back;
    this.product = new Product();
}

You can try that version here.

answered Oct 29, 2010 at 18:12

Nick Craver

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2 Comments

etoisarobot Over a year ago

Thanks. I tried that also but it was failing before it got to the alert because of how I was trying to set the front and back properties. Can I ask what "this.front = values && values.front || "default";" does in english?

Nick Craver Over a year ago

@TooFat - It's checking that values isn't falsy (undefined in this case) before trying to get a property from it, if it's false it'll immediately go to the OR (||) and grab the default.

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