Select URL from the Link To menu.
In the example above, the code will trigger an alert in the browser with "test" as the text in the alert.
You can apply the same type of code as a button action via the Buttons & Forms panel (Window > Interactive).
To do so, add a Go To URL action to your button.
When you export with in5 (in5 > Export HTML5 with in5...), you'll send this in action.