Current object property as value in same object different property

Question

Sorry for such a random title, but have no idea how to explain it better. And therefore, no idea if this is a duplicate question or not.

So, when declaring a new object, I'm looking to calculate the giga value:

var myObject = {
    super : 1,
    mega : 5,
    uber : 100,
    giga : this.super + this.mega + this.uber // super + mega + uber doesn't cut it either..
};

But this doesn't work, so, any ways of doing this while declaring, or not possible?

Hope I've made myself clear and thanks in advance!

possible duplicate of [Self-references in object literal declarations](http://stackoverflow.com/questions/4616202/self-references-in-object-literal-declarations) — Felix Kling, Nov 07 '11 at 13:07

score 6 · Accepted Answer · answered Nov 07 '11 at 13:13

6

In Javascript 1.5 you can use the get keyword to define a getter

var obj = {
    super : 1,
    mega : 5,
    uber : 100,
    get giga() {
        return this.super + this.mega + this.uber;
    }
};

alert(obj.giga) // 106

more on this http://robertnyman.com/2009/05/28/getters-and-setters-with-javascript-code-samples-and-demos/

answered Nov 07 '11 at 13:13

georg

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That will completely fall over on non-ES5 browsers. Please use `Object.defineProperty` to define getter/setters – Raynos Nov 07 '11 at 13:14
There is no specification whether I'm interested in ES5 or ES4 or ESx, I see no reason for the downvote. In fact, this is the cleanest answer so far. – tomsseisums Nov 07 '11 at 13:44

score 4 · Answer 2 · answered Nov 07 '11 at 12:58

I assume you have a really good reason for the need to do this inline, otherwise such trickery is not really a good idea.

Here is what I came up with:

var myObject = (function(){
    this.giga = this.super + this.mega + this.uber;
    return this;
}).call({
    super : 1,
    mega : 5,
    uber : 100
});

Raynos · Answer 3 · 2011-11-07T13:22:27.343

0

var myObject = {
    super : 1,
    mega : 5,
    uber : 100
};
myObject.giga = myObject.super + myObject.mega + myObject.uber;

edited Nov 07 '11 at 13:22

answered Nov 07 '11 at 13:02

Raynos

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There is a trailing comma, I had it as well when copypasting :P – Esailija Nov 07 '11 at 13:16
@Esailija why I copy paste fail? – Raynos Nov 07 '11 at 13:22
I don't understand the question. I meant I had the same error as you because I copypasted the OP's message, so I thought you had done so as well. – Esailija Nov 07 '11 at 13:27

Current object property as value in same object different property

3 Answers3

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