Difference between <!-- test1 //--> and <!-- -->

Question

User-1882290921 posted
These are both valid comments in HTML aren't they?  Is there any difference between the two? 

<!-- test1  //-->
<!-- test2  -->

Answer 1

User-837620913 posted
Yes they are.  You generally see the first one when using JavaScript:

<code>
<script type="javascript">
<!-- This begin HTML comment hides javascript from older browsers
// javascript code goes here
// use the // for comments in JavaScript, otherwise the --> would create a JavaScript error
// -->
</script>
</code>