Block form submit if no one checkbox checked

I need help because confused how to block form submit if no one checkbox checked.

<form id="send-invite-form">
   <input type="checkbox" class="invitation-friends" value="875" />
   <input type="checkbox" class="invitation-friends" value="394" />
   <button type="submit">Send</submit>
</form>

// Submit invinite
var $form = $( '#send-invite-form' );
var $checkbox = $( 'input[class^="invitation-friends"]' );

$form.on( 'submit', function(e) {
  $.each( $checkbox, function(index, value) {
    if( !$(value).is(':checked') ) {
      alert( 'Opps! You not select friends.' );
      e.preventDefault();
    }
  });
});

The code check every checkbox. I don't want it. I want if one checkbox checked, the form can submit. If no one checked, bail submit.

Please help.