How to split the words in given paragraph using javascript?

Html page:

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

<p id="P3"></p>

Javascript page:

<script>

    function myFunction()

    {

        var str = "How are you doing today?";

        var res = str.split(" ");

        document.getElementById("demo").innerHTML = res;

    }

</script>

Output:

How,are,you,doing,today?