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<!DOCTYPE html> 
<html> 
<body> 
<h1>HTML DOM Events</h1>
<h2>The onvolumechange Event</h2>

<video id="myVideo" width="320" height="240" controls>
  <source src="movie.mp4" type="video/mp4">
  <source src="movie.ogg" type="video/ogg">
  Your browser does not support the video tag.
</video>

<p>Try to change the volume.</p>

<button onclick="setHalfVolume()" type="button">Set volume to 0.2</button>
<button onclick="setFullVolume()" type="button">Set volume to 1.0</button>

// Attach a "volumechange" event to the video:
video.addEventListener("volumechange", getVolume);

// Display the current audio volume:
function getVolume() { 
  document.getElementById("demo").innerHTML = "The audio volume is: " + video.volume;
}

// Set the audio volume to 0.2
function setHalfVolume() { 
  video.volume = 0.2;
}

// Set the audio volume to 1.0 (the highest)
function setFullVolume() { 
  video.volume = 1.0;
} 
</script>

</body> 
</html>