the problem is your target is not
<div class=" tile tile-big tile-5" id="three" name = "Launch" >
but
<p>Launch Application </p>
which does not have "name" attribute that is why you get null try to add name attribute to it and you will get right alert.
try this
<div class=" tile tile-big tile-5" id="three" name = "Launch" onclick="testAlert(event)">
<div name = "Launch2"><p name = "Launch3">Launch Application </p></div>
</div>
<script>
function testAlert(event)
{
var target = event.target || event.srcElement;
alert(target.getAttribute('name'));
}
</script>
you will get the answer