微信小程序实现验证码获取倒计时效果

<button disabled='{{disabled}}' 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: '重新发送',
   currenttime:61,
   disabled: false 
  })
  }
 }, 100) 
 },
 getverificationcode(){
 this.getcode();
 var that = this
 that.setdata({
  disabled:true
 })
 },

})