<!DOCTYPE html>
<html>
<body>
<img id="myImg" src="compman.gif" alt="Crazy computerman" width="107" height="98">
<p>Click the button to change the alternate text of the image.</p>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
function myFunction() {
document.getElementById("myImg").alt = "newAlternateText";
document.getElementById("demo").innerHTML = "The value of the alt attribute was changed from 'Crazy computerman' to 'newAlternateText'";
}
</script>
</body>
</html>