控制树形结构全选、取消全选，展开收起

<template><div><!-- 添加 ref="tree" 属性--><el-tree:data="data"show-checkboxdefault-expand-allnode-key="id"ref="tree"highlight-current:props="defaultProps"></el-tree><div class="buttons"><el-button @click="allExpanded">折叠/展开</el-button><el-button @click="allChecked">全选</el-button><el-button @click="resetChecked">清空</el-button></div></div>
</template><script>export default {methods: {// this.$refs.tree  tree是上面控件 el-tree 的 ref 属性的值allExpanded(){// 展开还是收起this.expanded = !this.expanded;var treeNodeList = this.$refs.tree.store._getAllNodes();for (var i = 0; i < treeNodeList.length; i++) {treeNodeList[i].expanded = this.expanded;}},allChecked() {// 将根节点赋值上去this.$refs.tree.setCheckedKeys([1,2,3]);},resetChecked() {// 将选中设置为空this.$refs.tree.setCheckedKeys([]);}},data() {return {expanded:true,data: [{id: 1,label: '一级 1',children: [{id: 4,label: '二级 1-1',children: [{id: 9,label: '三级 1-1-1'}, {id: 10,label: '三级 1-1-2'}]}]}, {id: 2,label: '一级 2',children: [{id: 5,label: '二级 2-1'}, {id: 6,label: '二级 2-2'}]}, {id: 3,label: '一级 3',children: [{id: 7,label: '二级 3-1'}, {id: 8,label: '二级 3-2'}]}],defaultProps: {children: 'children',label: 'label'}};}};
</script>