获取父级的所有子组件，即使通过路由器出口渲染也是如此

methods: {
  getAllChildComponents() {
    let children = [];
    this.$children.forEach(child => {
      children.push(child);
      if (child.$children.length > 0) {
        children = children.concat(child.getAllChildComponents());
      }
    });
    return children;
  }
}

let allChildComponents = this.$parent.getAllChildComponents();