<!DOCTYPE html>
<html lang="en-US">
<body>
<p>Change my color</p>
<p>Click on the button to set 'style' for the above paragraph.</p>
<button onclick="myFunction()">Click Me</button>
<script>
var elem = document.getElementsByTagName("p")[0];
function myFunction(){
elem.setAttribute("style", "color:red;")
}
</script> </body>
</html>