<!DOCTYPE html>
<html>
<body>
<h1>With "use strict":</h1>
<h3>Using an object without declaring it, is not allowed.</h3>
<p>Activate debugging in your browser (F12) to see the error report.</p>
<script>
"use strict";
x = {p1:10, p2:20}; // This will cause an error (x is not defined).
</script>
</body>
</html>