Adding the type annotations required for Qt Quick Compiler

[Asperamanca]

I have the following QML signal handler:

onActiveTranslationChanged: function (translation)
{
   // Do something with translation
}

This gives me the warning:

:-1: warning: Could not compile binding for onActiveTranslationChanged: Functions without type annotations won't be compiled [compiler]

However, when I try to add type annotations like so

onActiveTranslationChanged: function (translation: vector2d)

I get the error:

error: Type annotations are not permitted in function parameters in JavaScript functions

How do I do it right?

[Asperamanca]

Answering my own question.
The simplest way seems to sidestep the issue by using the component's property value instead of the signal handler parameter:

    DragHandler
    {
        id: dragHandler
        // other properties
        onActiveTranslationChanged:
        {
            // Use dragHandler.activeTranslation instead of parameter
        }
    }