Single line comments start with //.
<script type="text/javascript">
// Write a heading
document.write("<h1>This is a heading</h1>");
// Write two paragraphs:
document.write("<p>This is a paragraph.</p>");
document.write("<p>This is another paragraph.</p>");
</script>
Multi line comments start with /* and end with */.
<script type="text/javascript">
/*
The code below will write
one heading and two paragraphs
*/
document.write("<h1>This is a heading</h1>");
document.write("<p>This is a paragraph.</p>");
document.write("<p>This is another paragraph.</p>");
</script>
Browsers that do not support JavaScript, will display JavaScript as page content.
To prevent them from doing this, just add an HTML comment tag <!-- before the first JavaScript statement, and a --> (end of comment) after the last JavaScript statement.
<script type="text/javascript">
<!--
document.getElementById("demo").innerHTML=Date();
//-->
</script>
