<!DOCTYPE html>
<html>
<body>

<p><a id="myAnchor" href="../../www.microsoft.com/index.html">www.microsoft.com</a></p>

<p>Click the button to change the value of the href attribute of the link above to "www.cnn.com".</p>

<button onclick="myFunction()">Try it</button>

<p id="demo"></p>

<script>
function myFunction() {
    document.getElementById("myAnchor").href = "http://www.cnn.com/";
    document.getElementById("demo").innerHTML = "The link above now goes to www.cnn.com.";
}
</script>

</body>
</html>