Explicit use of computed? What does a computed expression like this: this.isBusy = ko.computed(function() { return self._isBusy() || self._queryIsBusy(); }); have to do with <div data-bind="visible: _isBusy() || _queryIsBusy()" ></div> Internally knockout creates a computed out of an expression in a bindinghandler. Ko does not parse the expression in the html above to register the variables _isBusy or _queryIsBusy. Consequenses What does this mean for your code? If you have something below bu[...]