javascript array member of object

Question

I would like to create in javascript an object that contains an array of other objects. i.e.

var xobj = {
    d: 0,
    e: 0,
    f: 0
};

var topObj = {
    x: [],
    a: 0,
    b: 0,
    c: 0
};

topObj.x[0].d = 1;
topObj.x[0].e = 2;
var xx = topObj.x[0].d + topObj.x[0].e;

console.log( xx );

I would like topObj.x to be an array of xobj.

I am getting:

Uncaught TypeError: Cannot set property 'd' of undefined

TGH · Accepted Answer · 2013-05-14 04:51:05Z

2

You can do that, but you have to populate the array with instances of the object (xobj):

topObj.x.push(xobj);

answered May 14, 2013 at 4:51

TGH

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3 Comments

gene Over a year ago

Yeap, that works. I guess I have a follow up question: is there a way to declare an array of objects as a property of another object?

TGH Over a year ago

Yes, you can initialize "x" to some existing array object instead of an empty array.

gene Over a year ago

After some further testing this does not do exactly what I want. It works on a first element of the array, but all additional elements of the array "x" end up references of the one variable xobj. If I modify one - I modify them all. I would like for array "x" to be an array of different instances of xobj. I.E. if I set topObj.x[1].d = 2; I do not want it to affect [0]. right now it does.

James Daly · Accepted Answer · 2013-05-14 04:59:44Z

0

if you wanted just the values in the xobj to be appended to the array I would create something like this

for (prop in xobj) {
    topObj.x.push(xobj[prop])
}

answered May 14, 2013 at 4:59

James Daly

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