How can I associate a file type with a powershell script?

Question

I have a very powershell script that works perfectly and does:

Param(
  [string]$fileName
) 

echo \"Woo I opened $fileName\"

When I run it on

Answer 1

For those like me who got here looking for general file types associations, I ended up using this function:

Function Create-Association($ext, $exe) {
    $name = cmd /c "assoc $ext 2>NUL"
    if ($name) { # Association already exists: override it
        $name = $name.Split('=')[1]
    } else { # Name doesn't exist: create it
        $name = "$($ext.Replace('.',''))file" # ".log.1" becomes "log1file"
        cmd /c 'assoc $ext=$name'
    }
    cmd /c "ftype $name=`"$exe`" `"%1`""
}

I struggled with proper quoting from @Ansgar Wiechers's answer but finally got it right :)