code: function (event) {
              if (this.props.entry.get("rename")) {
                  event.stopPropagation();
                  return;
              }
  
              if (event.button !== LEFT_MOUSE_BUTTON) {
                  return;
              }
  
              var isOpen = this.props.entry.get("open"),
                  setOpen = isOpen ? false : true;
  
              if (event.metaKey || event.ctrlKey) {
                  // ctrl-alt-click toggles this directory and its children
                  if (event.altKey) {
                      if (setOpen) {
                          // when opening, we only open the immediate children because
                          // opening a whole subtree could be really slow (consider
                          // a `node_modules` directory, for example).
                          this.props.actions.toggleSubdirectories(this.myPath(), setOpen);
                          this.props.actions.setDirectoryOpen(this.myPath(), setOpen);
                      } else {
                          // When closing, we recursively close the whole subtree.
                          this.props.actions.closeSubtree(this.myPath());
                      }
                  } else {
                      // ctrl-click toggles the sibling directories
                      this.props.actions.toggleSubdirectories(this.props.parentPath, setOpen);
                  }
              } else {
                  // directory toggle with no modifier
                  this.props.actions.setDirectoryOpen(this.myPath(), setOpen);
              }
              event.stopPropagation();
              event.preventDefault();
          }
docs: If you click on a directory, it will toggle between open and closed.