<!DOCTYPE html>
<html>
<body>
<p>Click on "My Button" to display its value attribute.</p>
<button id="myBtn" name="myname" value="myvalue" onclick="alert(this.value)">My Button</button>
<p>Click on "Try it" to change the value attribute of "My Button".</p>
<button onclick="myFunction()">Try it</button>
<p><b>Tip:</b> Click on "My Button" before and after you have clicked on "Try it".</p>
<script>
function myFunction() {
document.getElementById("myBtn").value = "newButtonValue";
}
</script>
</body>
</html>