How to mute all sound in a page with JS?

How can I mute all sound on my page with JS?

This should mute HTML5 <audio> and <video> tags along with Flash and friends.

Rule #1: Never enable audio autoplay upon page loading.

Anyway I'll show for HTML5 using jQuery:

// WARNING: Untested code ;)

window.my_mute = false;

$('#my_mute_button').bind('click', function(){

    $('audio,video').each(function(){

        if (!my_mute ) {

            if( !$(this).paused ) {
                $(this).data('muted',true); //Store elements muted by the button.
                $(this).pause(); // or .muted=true to keep playing muted
            }

        } else {

            if( $(this).data('muted') ) {
                $(this).data('muted',false);
                $(this).play(); // or .muted=false
            }

        }
    });

    my_mute = !my_mute;

});

Flash Media Players depends on the custom API (hopefuly) exposed to JavaScript.

But you get the idea, iterate through media, check/store playing status, and mute/unmute.