<!DOCTYPE html>
<html>
<body>
<h1>With "use strict":</h1>
<h3>For security reasons, eval() is not allowed to create variables in the scope from which it was called.</h3>
<p>Activate debugging in your browser (F12) to see the error report.</p>
<script>
"use strict";
eval ("var x = 2");
alert (x); // This will cause an error
</script>
</body>
</html>