<button type="primary" bindtap="btnclick">按钮</button>
<modal title="标题" confirm-text="确认" cancel-text="取消" hidden="onOff" bindconfirm="modalConfirm" bindcancel="modalCancel">
这里是会话内容
</modal>

//获取应用实例
const app = getApp()
Page({
  data: {
      onOff:true 
  }, 
  btnclick:function(){
      var onOff = this.data.onOff;
      this.setData({onOff:!onOff});
  }
})