deferred observable

gistfile1.txt

    ko.extenders.deferred = function(targetObservable, startingVal) {
        //create a writeable computed observable to intercept writes to our observableo
        targetObservable.loading = ko.observable(startingVal);

        targetObservable.promise = function(x){
            targetObservable.loading(true);
            targetObservable.deferred = x;
            x.done(function(returnedTarget){
                targetObservable(returnedTarget);
                targetObservable.loading(false);
            });
        };

        return targetObservable;
    };