TypeError: Object.observe is not a function about observe-js HOT 2 CLOSED

    Platform.performMicrotaskCheckpoint(function(){
        Object.observe(appState, function(changes){
            console.log('application state changed *from* this :', appStateOldValue);
            console.log('application state changed to :', appState);
            appStateOldValue = _.clone(appState);
        });
    });

   Platform.performMicrotaskCheckpoint(function(){
        //now it's ok
        Object.observe(obj, function(changes){

        });
    });