Tryit Editor v2.7

Edit This Code:
<!DOCTYPE html>
<html>
<body>

<p>The first p element in the document.</p>
<p>Another p element.</p>

<p>Click the button to find out how many p elements there are in this document.</p>

<button onclick="myFunction()">Try it</button>

<p id="demo">I am also a p element.</p>

<script>
function myFunction() {
    var nodelist = document.getElementsByTagName("P").length;
    document.getElementById("demo").innerHTML = nodelist;
}
</script>

</body>
</html>