<!DOCTYPE html>
<html>
<head>
    <script>
    var mediaElement;
    function createMediaElement(parameters) {
        if (parameters.type === 'video')
            mediaElement = document.createElement('video');
        else if (parameters.type === 'audio')
            mediaElement = document.createElement('audio');
        else
            throw 'Necessary parameter not provided';

        if (parameters.autoplay)
            mediaElement.autoplay = true;

        if (parameters.muted)
            mediaElement.muted = true;

        if (parameters.controls)
            mediaElement.controls = true;

        if (parameters.hasAudio)
            mediaElement.src = 'video-with-audio.mp4';
        else
            mediaElement.src = 'video-without-audio.mp4';

        document.body.appendChild(mediaElement);
    }

    function playing() {
        window.webkit.messageHandlers.testHandler.postMessage('playing');
    }

    function notPlaying() {
        window.webkit.messageHandlers.testHandler.postMessage('not playing');
    }

    function play() {
        mediaElement.play().then(playing, notPlaying);
    }

    function unmute() {
        mediaElement.muted = false;
    }
    </script>
</head>
<body>
</body>
</html>