function timer() {
        let tick = 0;
        let clockOn=false;

        let myInterval = null;

        function step() {
            tick++;
            let seconds = ('0' + tick % 60).slice(-2);
            $('#seconds').text(seconds);
            let minutes = ('0' + Math.floor(tick / 60)).slice(-2);
            $('#minutes').text(minutes);
            let hours = ('0' + Math.floor(minutes / 60)).slice(-2);
            $('#hours').text(hours);
        }

        function myStopFunction() {
            clearInterval(myInterval);
            console.log('clear');
        }


        $('#start-timer').on('click', function(){
            myInterval = setInterval(step, 1000);
        });


        $('#stop-timer').on('click', myStopFunction);
    }