Angular Rx safeSubscribe

rx-angular.safeSubscribe.js

rx.Observable.prototype.safeSubscribe = function(scope, fn, err, cmp) {
    var disposable = this.safeApply(scope, fn).subscribe(angular.noop, err, cmp);
    scope.$on("$destroy", function() {
        disposable.dispose();
    });
    return disposable;
};