Reply To: Displaying n words on screen

You could test the value of the Var element right after you increment it in the callback to see if the updated index goes beyond the number of words, and if so, wait for a key press on K to stop the timer:

newKey("NEXT", " ")
    .callback(
        getVar("nextWordStartsAt").test.is(v=>v<row.Words.split('_').length).success(
            getVar("listOfWords")
                .set(getVar("nextWordStartsAt"))
                .set(v=>row.Words.split('_').slice(v,v+10).join("<br>"))
            ,
            getText("words").text( getVar("listOfWords") )
            ,
            getVar("nextWordStartsAt")
                .set(v=>v+10) // update the index
                .test.is(v=>v>=row.Words.split('_').length).success( // if the index is greater than the # of words
                    newKey("K").wait() // wait for a key press on K
                    ,
                    getTimer("recording").stop() // stop the timer
                )
        )
    )

Jeremy