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<!DOCTYPE html>
<html>
<body>
<h3>A demonstration of how to access a SUB element</h3>
<p>Click the button to set the color of <sub id="mySub">this subscript text</sub> to red.</p>
<button onclick="myFunction()">Try it</button>
<script>
function myFunction() {
  var x = document.getElementById("mySub");
  x.style.color = "red";
}
</script>
</body>
</html>