It would be nice if we could give a delegate function to "textRole" and "valueRole".

Right now you have to supply textRole in the form of string, which breaks if you need more advanced logic for generating said text. I suggest we add something that lets us use an anonymous lambda instead, that takes the model-data as parameter and returns the string to display.

Ideally I would like a user-story similar to this:

ComboBox {
    model: myJsArray
    textRoleFn: (modelData) => { return modelData.someString + "Additional data" }
}