<!DOCTYPE html>
<html lang="en-US">
<body>
<p>P 1</p>
<p>P 2</p>
<p>P 3</p>
<button onclick="myFunction()">Click Me</button>
<script>
function myFunction(){
var x = document.getElementsByTagName("p");
var txt = "Hello there!";
//Try to change '0' to '1'
x[0].innerHTML = txt;
}
</script> </body>
</html>