<template>
  <div class="ontainer">
    <el-tree
      :props="props"
      :load="loadNode"
      lazy
      show-checkbox
      @check-change="handleCheckChange">
    </el-tree>
  </div>
</template>


<script>
  export default {
    data() {
      return {
        props: {
          label: 'name',
          children: 'zones'
        },
        count: 1
      };
    },
    methods: {
      handleCheckChange(data, checked, indeterminate) {
        // 節點所對應的物件、節點本身是否被選中、節點的子樹中是否有被選中的節點
        console.log(data, checked, indeterminate);
      },
      handleNodeClick(data) {
        console.log(data);
      },
      loadNode(node, resolve) {
        console.log(node)
        if (node.level === 0) {
          let jiashuju = [{ name: 'region1' }, { name: 'region2' },{ name: 'region3' }]
          return resolve(jiashuju);
        }
        if (node.level > 3) return resolve([]);

        var hasChild;
        if (node.data.name === 'region1') {
          hasChild = true;
        } else if (node.data.name === 'region2') {
          hasChild = false;
        } else {
          // console.log(Math.random())
          hasChild = Math.random() > 0.5;
        }

        setTimeout(() => {
          var data;
          if (hasChild) {
            data = [{
              name: 'zone' + this.count++
            }, {
              name: 'zone' + this.count++
            }];
          } else {
            data = [];
          }

          resolve(data);
        }, 500);
      }
    }
  };
</script>