JavaScript對象沒有任何辦法能引用他們自身，所以你需要通過myViewModelObject.myDependentObservable = ... 的形式添加依賴監控屬性到view model對象上。 你不能直接在view model里聲明他們，換句話說，你不能寫成下面這樣：
varviewModel = {
myDependentObservable: ko.dependentObservable(function() {
...
},/*can't refer to viewModel from here, sothis doesn't work*/)
}
… 相反你必須寫成如下這樣：
varviewModel = {
//Add other properties here as you wish
};
viewModel.myDependentObservable = ko.dependentObservable(function() {? ??
...
}, viewModel);//This is OK
