Tryit Editor v2.9

Edit This Code:
<!DOCTYPE html>
<html>
<body>

<p>The addEventListener() method is not supported Internet Explorer 8 and earlier versions.</p>

<p>This example demonstrates a solution that will work for all browsers.</p>

<button id="myBtn">Try it</button>

<script>
var x = document.getElementById("myBtn");
if (x.addEventListener) {
    x.addEventListener("click", myFunction);
} else if (x.attachEvent) {
    x.attachEvent("onclick", myFunction);
}

function myFunction() {
    alert("Hello World!");
}
</script>

</body>
</html>