<!DOCTYPE html>
<html>
<body>

<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><br>

<button onclick="enableLoop()" type="button">Enable loop</button>
<button onclick="disableLoop()" type="button">Disable loop</button>
<button onclick="checkLoop()" type="button">Check loop status</button>

<script>
var x = document.getElementById("myVideo");

function enableLoop() {
    x.loop = true;
    x.load();
}

function disableLoop() {
    x.loop = false;
    x.load();
}

function checkLoop() {
    alert(x.loop);
}
</script>

</body>
</html>