rc-menu 源码里的一点问题

Question

clearMenuItemMouseLeaveTimer() {
    const props = this.props;
    let callFn;
    const parentMenu = props.parentMenu;
    if (parentMenu.menuItemMouseLeaveTimer) {
      clearTimeout(parentMenu.menuItemMouseLeaveTimer);
      parentMenu.menuItemMouseLeaveTimer = null;
      if (callFn && parentMenu.menuItemMouseLeaveFn) {
        parentMenu.menuItemMouseLeaveFn();
      }
      parentMenu.menuItemMouseLeaveFn = null;
    }
  },

上面申明了 callFn，为什么下面会有个 if 语句里面有 callFn 呢，好像没有被赋值呀？

源码地址：

https://github.com/react-comp...