<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8"/>
<title></title>
<meta charset="utf-8" />
<script src="js/jquery-1.8.3.js"></script>
<script type="text/javascript">
$(function () {
$(':text').blur(function () {
if ($(this).val().length == 0) {
$(this).css('backgroundColor', 'red');
} else {
$(this).css('backgroundColor', '');
}
});
});
</script>
</head>
<body>
<input /><input /><input /><input />
</body>
</html>