vant-weapp/example/pages/tree-select/index.js

import Page from '../../common/page';
import config from './config';

Page({
  data: {
    items: [{
      text: '所有城市',
      children: [...config.pro1, ...config.pro2]
    }, {
      text: config.pro1Name,
      children: config.pro1
    }, {
      text: config.pro2Name,
      children: config.pro2
    }, {
      text: config.pro3Name,
      disabled: true,
      children: config.pro3
    }
    ],
    mainActiveIndex: 0,
    activeId: 0,
    mainActiveIndexMulti: 0,
    activeIdMulti: []
  },

  onClickNav({ detail }) {
    this.setData({
      mainActiveIndex: detail.index || 0
    });
  },

  onClickItem({ detail }) {
    const activeId = this.data.activeId === detail.id ? null : detail.id;

    this.setData({ activeId });
  },

  onClickNavMulti({ detail }) {
    this.setData({
      mainActiveIndexMulti: detail.index || 0
    });
  },

  onClickItemMulti({ detail }) {
    const { activeIdMulti } = this.data;
    const idx = activeIdMulti.indexOf(detail.id);
    if (idx > -1) {
      activeIdMulti.splice(idx, 1);
    } else {
      activeIdMulti.push(detail.id);
    }

    this.setData({ activeIdMulti });
  }
});