javascript - Boolean of one element with jQuery -

i have code

<main class="ok">my text</main>  <script>  $(document).ready(function() {      if ( $('body').not('main.ok') ) {     // or if ( boolean ( $('main.ok') ) == false ) {           // main element not available          alert (' main element "ok class" not available ');      } else {           alert (' main element "ok class" available ');      }  });  </script> 

but code doesn't work !

and alert

main element "ok class" not available

so u guys suggest me ?

use hasclass()

determine whether of matched elements assigned given class.

$('body main').length && $('body main').hasclass('ok') 

code

if ($('body main').length && $('body main').hasclass('ok')) {     alert(' main element "ok class" available '); } else {     alert(' main element "ok class" not available '); }