1，在组件中设置展开收缩开关 default-expand-all="isExpand"
2，展开收起触发按钮
<div class="tree-foot clearfix"> <el-button class="fr" size="mini" plain type="primary" icon="el-icon-caret-top" @click="CloseFun">关闭</el-button> <el-button class="fr" size="mini" plain type="primary" icon="el-icon-caret-bottom" @click="ExpandFun">展开</el-button> </div>
3，这里采用ref来获取DOM。至于this.$refs.navtree.toString().split(‘,‘).length为什么不直接获取长度，因为原型对象上没有length方法（再问，我也不知道了）
// 展开收起
ExpandFun(){
console.log(this.$refs.navtree[0].store._getAllNodes().length)
// let type = Object.prototype.toString.call(this.$refs.navtree)
this.isExpand = true;
this.DynamicScaling()
}
CloseFun(){
this.isExpand = false;
this.DynamicScaling()
}
DynamicScaling(){
for(let i=0;i<this.$refs.navtree.toString().split(‘,‘).length; i++){
for(let j=0; j<this.$refs.navtree[i].store._getAllNodes().length; j++){
this.$refs.navtree[i].store._getAllNodes()[j].expanded= this.isExpand;
}
}
}
原文：https://www.cnblogs.com/chuanq/p/11525938.html