var audio = new Audio('audio_file.mp3');
audio.play();
<code></p>

<p>Same with displaying dynamic images (i'm using jquery here):</p>

<p><code><img id="imagepreview">
<input type="text" val="" id="imagename">
<input type="button" val="Load Image" id="loadbutton"
...
<script>
$(window).on('load', function() {
    $('#loadbutton').on('click', function() {
        var imagename = $('#imagename').val();
        var imgpath = '/preview/' + imagename; // Input validation? Nah, there are no bad people on the internet ;-)
        $('#imagepreview').attr('src', imgpath); // Triggers loading of the new image source
    });
});
</script>