Write C++ or JS function into QML

See more:

C++

Javascript

QT

I have a QML file where i am displaying update of my device of the network.

Text{
    x: 110; y: 84
    text : pIso.gVolt(pIso.gVolt); color : "white"; font.pointSize: 6; textFormat: Text.StyledText


    onTextChanged: {
//here I want to add the code to write update value of device into log file(CSV)
}
}

I want to get the idea do I need to call the C++ function OR Add code directly in QML file for writing and appending into log file.??
Is it possible to do this with Java script??

What I have tried:

This is first time i am interacting with QML. I dont know how to hook c++ in QML file