01 | 02 | 03 | 04 | 05 

  <body class="index">
    <!--...-->
  </body>
  

  var MESSAGE = 'Added after document be ready and because \'.index\' selector was found!';

  var awaitAndAppendContent = function() {
    var $content = $( '<h2>' ).text( MESSAGE );
    var appendContent = function() { $( 'body' ).append( $content ) }

    setTimeout( appendContent, 700 );
  }

  $.behavior.to( '.index' ).ifPresent( awaitAndAppendContent );