object of objects orientation - selector, appendTo(), set attributes ...

[dedtadeas]

Hello,
I have following object of objects:
var xmlObject = {"@attributes":{"id":"3","name":"Cell"},
"image":"img1.jpg",
"linkItem":[
{"@attributes":{"itemType":"reaction","itemId":"1","itemName":"O2 bubble exchange"},"area":[{"@attributes":{"width":"50","height":"250","top":"0","left":"150"}},{"@attributes":{"width":"100"," height":"250","top":"100","left":"150"}}],"point":[{"@attributes":{"top":"200","left":"20"}},{"@attributes":{"top":"20","left":"200"}}]},
{"@attributes":{"itemType":"entity","itemId":"1","itemName":"CO2"},"area":[{"@attributes":{"width":"100","height":"250","top":"30","left":"250"}},{"@attributes":{"width":"10", "height":"50","top":"300","left":"150"}}],"point":{"@attributes":{"top":"200","left":"200"}}
}]};

now the thing is that I dont really understand, how to operate with this kind of object.
select problem:
var x = xmlObject.linkItem[itemId = 1]; works fine , but
var x = xmlObject.linkItem[itemType = "reaction"]; is not working ... %) why ?

add object to object problem(e.g. area to specified linkItem):
how to add object to object ? or just changing attributes of existing object in object (e.g. change width of specified area in specified item)?

I understand objects in javascript, but nested objects are quite different :/

Thanx a lot for some post

[ReFreezed]

Here's an example how nested objects works:

var object = {
    'attribute1': 'foo',
    'attribute2': 'bar',
    'attribute3': [
        {
            'attr1': 123,
            'attr2': 456
        },
        {
            'attr1': 'abc', // we change this value to "foobar" later
            'attr2': 'def'
        }
    ]
};

alert(object['attribute2']); // alerts "bar"
alert(object['attribute3'][0]['attr2']); // alerts 456
alert(object['attribute3'][1]['attr1']); // alerts "abc"

object['attribute3'][1]['attr1'] = 'foobar';
alert(object['attribute3'][1]['attr1']); // now alerts "foobar"

To explain your problem: when you write xmlObject.linkItem[itemId = 1]; two things happen. First, you're assigning the number 1 to the variable itemId, and second, you're accessing xmlObject.linkItem[1] (which works fine because there is an object at index 1 in the xmlObject.linkItem array).

When you're writing xmlObject.linkItem[itemType = "reaction"]; similar things happen. First, you're assigning the string "reaction" to the variable itemType, and second, you're accessing xmlObject.linkItem["reaction"]. However, the array xmlObject.linkItem does not have a reaction attribute, so you get 'undefined' back from that expression.

I hope that clarifies what happens.

Also note that the following two lines does the same thing - it's only two ways of writing it:

object['attribute1'] = 'hello';
object.attribute1 = 'hello';

alert(object['attribute1']);
alert(object.attribute1);