How do I ensure that the correct “this” is referred to in an event handler? Say you have an event-handler within a custom widget which looks like this:

MyWidget.prototype._someHandler = function(e) {
	alert(this);
}

and then later within the same class definition, register a handler with another class instance:

var anotherWidget = new AnotherWidget();
anotherWidget.addEventListener("changeSomething", this._someHandler);

When the handler gets triggered by a “changeSomething” event, the alert of the handler is being called. However, there is a problem in that ‘this’ now refers to an object of class AnotherWidget and not to the instance of MyWidget. To solve this problem, use:

anotherWidget.addEventListener("changeSomething", this._handler, this);