>
        var x = document.getElementById("demo");
        var positions = [];


        var audio = new Audio('sound.mp3');

        function playSound() {
            audio.play();
        }

        function vibrate() {
            window.navigator.vibrate([200]);
        }

        if (navigator.geolocation) {
            console.log("navigator.geolocation exists");
            navigator.geolocation.watchPosition(function(position, error) {
                console.log("xxx", position, error);
          