code: function (target, e) {
              if (this.current_plugin !== this.plugin_count || e.altKey || e.ctrlKey || e.shiftKey || e.metaKey) {
                  return;
              }
  
              switch (e.which) {
                  case 83: // W
                  case 65: // A
                  case 40: // DOWN
                  case 37: // LEFT
                      e.preventDefault();
                      this.moveByKey(false);
                      break;
  
                  case 87: // S
                  case 68: // D
                  case 38: // UP
                  case 39: // RIGHT
                      e.preventDefault();
                      this.moveByKey(true);
                      break;
              }
  
              return true;
          }
docs: Keyborard controls for focused slider
  
  @param target {String}
  @param e {Object} event object
  @returns {boolean|undefined}