First Javascript

<!DOCTYPE html>
<html>
<head>
<script>
var x2 = "My First JavaScript Function";
var x1 = "Button 1";
function myFunction()
{
   var current = getHtml("test");
   setHtml("test", current == x1 ? x2 : x1);
}

function getHtml(id) { return document.getElementById(id).innerHTML; }

function setHtml(id, text) {
    document.getElementById(id).innerHTML = text;
}
</script>
</head>

<body>

<h1>My Web Page</h1>

<p id="test">Button 1</p>

<button type="button" onclick="myFunction()">Try me</button>

</body>
</html>