А так?
<!DOCTYPE html>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
:focus{
background-color: #228B22;
color: #FFFFFF;
}
</style>
<script>
document.addEventListener('DOMContentLoaded', function() {
document.addEventListener('focus',
function(event) {
document.querySelector('.show').innerHTML = document.querySelector('.selector:focus').tagName;
},true)
});
</script>
</head>
<body>
<p class="selector" tabindex="1">click me</p>
<input name="" class="selector" value="click me">
<button class="selector" >click me</button>
<div class="show"></div>
</body>
</html>