通过微信小程序如何实现验证码获取倒计时效果

<button disabled=&#39;{{disabled}}&#39; data-id="2" bindtap="getVerificationCode">
{{time}}
</button>

var interval = null //倒计时函数
Page({
 data: {
 date:'请选择日期',
 fun_id:2,
 time: '获取验证码', //倒计时 
 currentTime:61
 }, 
 getCode: function (options){
 var that = this;
 var currentTime = that.data.currentTime
 interval = setInterval(function () {
  currentTime--;
  that.setData({
  time: currentTime+'秒'
  })
  if (currentTime <= 0) {
  clearInterval(interval)
  that.setData({
   time: &#39;重新发送&#39;,
   currentTime:61,
   disabled: false 
  })
  }
 }, 100) 
 },
 getVerificationCode(){
 this.getCode();
 var that = this
 that.setData({
  disabled:true
 })
 },

})