Untitled

<!DOCTYPE html>
<html>
<body>

meh: <input type="text" id = "meh">

<p>Reda radi.</p>

<script>
var x = document.getElementById("meh");
x.addEventListener("focus", kadStisne);
x.addEventListener("blur", kadPusti);

function kadStisne() {
  var y = document.getElementById("meh");
  y.style.background = "yellow";
  document.getElementById("meh") = y;
}

function kadPusti(){
  var y = document.getElementById("meh");
  y.style.background = "red";
  document.getElementById("meh") = y;
}
</script>

</body>
</html>