Try it Editor: Global "use strict" declaration.

Edit This Code :


<!DOCTYPE html>
<html>
<body>

<h2>Global "use strict" declaration.</h2>

<p>Activate debugging in your browser (F12) to see the error report.</p>

<script>
"use strict";
myFunction();

function myFunction() {
    y = 3.14;   // This will cause an error (y is not defined)
}
</script>

</body>
</html>

Result :