Good news is here! This feature is implemented in Safari 9.
Safari 9.0 lets you create custom controls for your HTML5 environment with JavaScript AirPlay. Use Safari WebKitPlaybackTargetAvailabilityEvent to detect Airplay availability, and then add your own controls for streaming audio and video to AirPlay devices.
Via What's New in Safari 9
Here is an example from HTML5 video and a button for AirPlay
// Detect if AirPlay is available // Mac OS Safari 9+ only if (window.WebKitPlaybackTargetAvailabilityEvent) { video.addEventListener('webkitplaybacktargetavailabilitychanged', function(event) { switch (event.availability) { case "available": AirPlayButton.show(); break; default: AirPlayButton.hide(); } AirPlayButton.on('click', function() { video.webkitShowPlaybackTargetPicker(); }); }); }
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