<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><body><p >Click the button get the URI of the document's namespace.</p><button onclick="myFunction()">Try it</button><p><strong>Note:</strong> Internet Explorer 8 and earlier does not support the namespaceURI property.</p><p id="demo"></p><script>function myFunction() { var x = document.documentElement.namespaceURI; document.getElementById("demo").innerHTML = x;}</script></body></html>