Question

Reading up on ComboBox component → Link

The last code example has this line request.url = ComboBox(evt.target).selectedItem.data;

What does ComboBox(evt.target) mean? Type casting? Why would you type cast?

For curiosity reasons, I replaced the last line of changeHandler() with it too: ComboBox(evt.target).selectedIndex = -1;. It works. Does it make the handler function more flexible, since I’m not referencing aCb instance?

Answer 1

you are casting the trigger of the event as a ComboBox. You do this to explictly say that this variable is of this type. You don’t have to most of the times but when you do you get these advantages

1. When you are checking what the type is
2. You get all of the methods in the type Class (In this case Combo Box) as autocomplete options in your IDE
3. Will throw an error if evt.target is not of type ComboBox after all
4. Also is a visual indicator of what variable it is. Very helpful when revisiting code