code: function() {
  
                      // beforeOpen callback
                      offsideSettings.beforeOpen();
  
                      // Turn on CSS transitions on first interaction with an Offside instance
                      if ( firstInteraction ) {
                          firstInteraction = false;
                          turnOnCssTransitions();
                      }
  
                      // If another Offside instance is already open,
                      // close it before going on
                      closeAll();
  
                      // Set global body active class for current Offside instance
                      addClass( body, offsideBodyOpenClass );
                      addClass( body, offsideBodyOpenSideClass );
  
                      // Add Offside instance open class
                      addClass( offside, offsideOpenClass );
  
                      // Update open Offside instances tracker
                      openOffsidesId.push( id );
  
                      // afterOpen callback
                      offsideSettings.afterOpen();
                  }
docs: Offside instance id Offside instance private methods