JS Replace

<!DOCTYPE html>
<html>
<body>
<button onclick="myFunction()">Try it</button>
<p id="demo">Paul,Paula,paul,sPaul,Paul,Paul</p>
<script>
  function myFunction() {
      var str = document.getElementById("demo").innerHTML;
      var txt = str.replace(/Paul/g,"Ringo");
      document.getElementById("demo").innerHTML = txt;
  }
</script>
</body>
</html>