QT Installer framework custom script

[mbaudot]

Hello,
I'm new to the world of QT and javascript, I've discovered QT Installer Framework recently and I can already do amazing things with it. However I have some issues to accomplish the following:

I'm creating an installer with several components in it (com.1 ; com.2 ; com.3). For a particular component (com.1), I would like to check if a folder exists or not, before starting installation process for this component. If the folder exists, prompt the user with a message and give him the choice to Retry or Cancel the installation.

Someone can help me to start with this?
Thank you very much in advance.

Matt