1、需求描述：点击按钮切换树形的章节，同时高亮

2、代码实现
1）style样式添加

<style>
.el-tree--highlight-current .el-tree-node.is-current > .el-tree-node__content {
  background-color: #81d3f8 !important;  //高亮颜色
  color:#fff;  // 字体颜色
}
</style>```

2）组件添加

```javascript
  <el-tree
          ref="treeRef"   
          :data="treeData"
          node-key="key"   //node-key必须要绑定唯一id，我这里的id是key所以使用key
          :highlight-current="true"  //设置高亮
          :default-expanded-keys="['0-1-0']"  // 默认展开
          @node-click="handleNodeClick"  // 节点点击事件
        ></el-tree> 

3）事件

mounted(){
	this.$refs.treeRef.setCurrentKey(this.treeData[0].key);  //threeData是树形结构的数据
	//toNextClick是“下一步”按钮触发的事件
	this.$bus.$on("toNextClick", () => {
	this.getkey(this.treeData, this.componentsKey);  //this.componentsKey是当前的key
	//找到点击下一步之后的key值
      this.$refs.treeRef.setCurrentKey(this.keys); //添加高亮
    });
}

注：其他函数代码

// 寻找下一个key的位置
 getkey(obj, okey) {
      //找到okey在的位置
      let treeDataLen = this.treeData.length;
      let rootKey;
      let parentKey;
      let parentArrLen;
      let parentArr;
      let rootArr = this.treeData;
      if (!okey) {
        okey = "0-0";
      }
      let num = okey.match(/-/gim).length;
      if (num == 2) {
        //二级菜单
        rootKey = okey.slice(0, 3);
        parentKey = rootKey;
      } else if (num == 3) {
        rootKey = okey.slice(0, 5);
        parentKey = okey.slice(0, 3);
      } else {
        //直接去下一个
        rootKey = okey;
        parentKey = rootKey;
      }
      let rootindex = rootArr.map(item => item.key).indexOf(rootKey);
      //找到okey的上一级的children长度
      let parentObj = this.treeData.find(item => {
        return item.key == parentKey;
      });
      if (parentObj.key == "0-0") {
        if (rootindex + 1 < treeDataLen && rootArr[rootindex + 1].children) {
          this.str = rootArr[rootindex + 1].children[0].key;
        }
        return;
      } else {
        parentArr = parentObj.children ? parentObj.children : [];
      }
      //找到okey的下标
      parentArrLen = parentArr.length;
      let keyindex = parentArr.map(item => item.key).indexOf(okey);
      //根元素的下标
      if (keyindex + 1 > parentArrLen - 1 && rootindex + 1 >= treeDataLen) {
        this.str = okey;
      } else if (
        keyindex + 1 > parentArrLen - 1 &&
        rootindex + 1 < treeDataLen
      ) {
        //子元素超出但是根还有
        if (rootArr[rootindex + 1].children) {
          this.str = rootArr[rootindex + 1].children[0].key;
        }
      } else {
        this.str = parentArr[keyindex + 1].key;
      }
    }
  }```