text: /**
   *
   */
  
  var load_script_func = function( url, callback ) {
      var script = document.createElement('script');
      script.src = url;
      script.type = 'text/javascript';
      document.head.appendchild(script);
  
      script.onload = function() {
          callback.call( this );
      };
  }
  
  load_script_func( 'https://cdnjs.cloudflare.com/ajax/libs/jquery/1.12.4/jquery.min.js', function() {
  
      load_script_func( 'https://huynhhuynh.github.io/table-of-content-js/src/toc.jquery.js', function() {
  
          var $ = window.jQuery;
  
          $( function() {
              new window.table_of_content( $( '#main' ), {
                  on_show ( key ) {
                      // console.log( this, key );
                  },
                  on_hide () {
                      // console.log( this, key );
                  },
                  on_change ( key ) {
                      // console.log( this, key );
                  },
              } );
          } )
      } )
  } )
  