This is the code. (I know that I must type here so many text to post my question, but please ignore this part in the parenthesis. It is due only to the rules of the site.)
I can not find the reason, but on screen only appears "{{adat}}".
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title> </title>
<script src="https://code.angularjs.org/1.8.2/angular.js">
</script>
<script type="text/javascript">
function todoc($scope) {
$scope.adat = "Szia!";
}
</script>
</head>
<body ng-app>
<div ng-controller="todoc">
<h1> {{adat}} </h1>
</div>
</body>
</html>