No output in Visual Studio Code

I'm learning JavaScript and I wrote a simple program in Visual Studio Code but there was no output what so ever when I attempted to run it.

class main{
    multiplier(x,y){
        return x*y
    }
    main(){
        let x,y
        x = window.prompt('Your favourite number')
        y = window.prompt('Your age')
        console.log(multiplier(x,y))
    }
}