SC Observer

gistfile1.js

UJAM.Node = SC.Object.extend({
    parentNode: null,
    childNodes: [],

    childsDidChange: function () {
        alert('child nodes changed');
    }.observes('childNodes'),

    addChild: function (node) {
        this.childNodes.push(node);
        this.notifyPropertyChange('childNodes');
    }
});

UJAM.root = UJAM.Node.create({});
UJAM.NodeObserver = SC.Object.extend({
    childsDidChange: function () {
        alert('child nodes changed');
    }.observes('UJAM.root.childNodes'),
});
UJAM.obs = UJAM.NodeObserver({});
UJAM.root.addChild(UJAM.Node.create({}));