$event is the event itself. The event binding (someevent) allows to bind to DOM events and to EventEmitter events. The syntax is exactly the same. For DOM events $event is the MouseEvent, KeyboardEvent, or the event value of the type of whatever event you listen to. For EventEmitter events the emitted value is available as … Read more
Reason is setState is asynchronous, you can’t expect the updated state value just after the setState, if you want to check the value use a callback method. Pass a method as callback that will be get executed after the setState complete its task. Why setState is asynchronous ? This is because setState alters the state … Read more
You have to use a named function so you can reference that specific handler when calling .unbind(), like this: function keyUpFunc(e) { if (e.keyCode == 27) { functionZzy(); } } $(document).keyup(keyUpFunc); Then later when unbinding: $(document).unbind(“keyup”, keyUpFunc);
I believe What you’re looking for is already part of the API in the ObservableCollection(T) class. Example: ObservableCollection<int> myList = new ObservableCollection<int>(); myList.CollectionChanged += new System.Collections.Specialized.NotifyCollectionChangedEventHandler( delegate(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e) { if (e.Action == System.Collections.Specialized.NotifyCollectionChangedAction.Add) { MessageBox.Show(“Added value”); } } ); myList.Add(1);
Java gives you a simple Observer pattern implementation for this kind of thing, but you’ll need to set your observed variable within a method that manages listener notifications. If you can’t extend Observable, you can either use composition (i.e., have an Observable instance in your class to manage notifications), or you can take a look … Read more
There is a tiny chance that SomethingHappened becomes null after the null check but before the invocation. However, MulticastDelagates are immutable, so if you first assign a variable, null check against the variable and invoke through it, you are safe from that scenario (self plug: I wrote a blog post about this a while ago). … Read more
Use the stopImmediatePropagation function of the jQuery event object. Keeps the rest of the handlers from being executed. This method also stops the bubbling by calling event.stopPropagation(). $(document).click(function(event) { alert(‘a’); event.stopImmediatePropagation(); return false; }); $(document).click(function() { alert(‘b’); });
When you divide the project into logical parts (for example with MVP), then the different parts sometimes need to communicate. Typical this communication is done by sending status changes, e.g.: user logged-in / logged-out. user navigated directly via URL to a page, so the menu needs to be updated. Using the event bus is quite … Read more
This is a good question, and I actually don’t think it can be done easily. (Some discussion on this) If it is super duper important for you to have this functionality, you could hack it like so: function singleClick(e) { // do something, “this” will be the DOM element } function doubleClick(e) { // do … Read more
You can pass extra data to an event handling function and can be accessed using event.data within the handler. $(document).on(‘dblclick’, ‘#an_tnam tr’, { extra : ‘random string’ }, function(event) { var data = event.data; // Prints ‘random string’ to the console console.log(data.extra); } You can also send extra data to any event you like when … Read more