Uncaught ReferenceError: commonL10n is not defined code example

Example: Uncaught ReferenceError: commonL10n is not defined

add_action( 'admin_footer', function () {
	?>
	<script>
		if ( typeof commonL10n === 'undefined' ) {
			var commonL10n = { dismiss : 'Dismiss' };
		}
	</script>
	<?php
}, 100 );