<html>
<body>
<p id="p1">This is a paragraph</p>
<p id="p2">This is another paragraph</p>
<p id="demo">Click the button to compare the position of the two paragraphs.</p>
<button onclick="myFunction()">Try it</button>
<script>
function myFunction()
{
var p1=document.getElementById("p1").lastChild;
var p2=document.getElementById("p2").lastChild;
var x=document.getElementById("demo");
x.innerHTML=p1.compareDocumentPosition(p2);
}
</script>
<p>
1: The two nodes do not belong to the same document.<br>
2: p1 is positioned after p2.<br>
4: p1 is positioned before p2.<br>
8: p1 is positioned inside p2.<br>
16: p2 is positioned inside p1.<br>
32: The two nodes has no relationship, or they are two attributes on the same element.</p>
<p><strong>Note:</strong> The compareDocumentPosition method is not supported in Internet Explorer 8 and earlier.</p>
<p><strong>Note:</strong> The returnvalue could also be a combination of values. I.e. the returnvalue 20 means that p2 is inside p1 (16) AND p1 is positioned before p2 (4).</p>
</body>
</html>