x
<html><body><p>"use strict" in a function will only cause errors in that function.</p><p>Activate debugging in your browser (F12) to see the error report.</p><script>x = 3.14; // This will not cause an error.myFunction();function myFunction() { "use strict"; y = 3.14; // This will cause an error (y is not defined).}</script></body></html>