ionic3+angular 倒计时效果

// 声明变量
  applicationInterval: any; // 定时器
  nextBtnText: String;
  nextBtnBool: Boolean;
  // 使用定时器，每秒执行一次
  ionViewDidEnter() {
    let that = this;
    let applicationPageOpenData: number = parseInt(((new Date().getTime() / 1000) + 120).toString()); //120是设置的秒数
    let nowDte: number;
    this.nextBtnText = "30秒后方可点击"; // 按钮文本
    this.nextBtnBool = false; // 按钮是否可点击标识
    this.applicationInterval = setInterval(() => {
      nowDte = parseInt((new Date().getTime() / 1000).toString());
      console.log(nowDte);
      let receiveDate = applicationPageOpenData - nowDte;
      if (receiveDate > 0) {
        let tss = this.s_to_hs(receiveDate);
        that.nextBtnText = tss + "秒后方可点击";
        
        console.log(this.s_to_hs(receiveDate));
      } else {
        that.nextBtnText = "下一步";
        that.nextBtnBool = true;
        // 停止定时器
        clearInterval(that.applicationInterval);
      }
    }, 1000);
  }
  s_to_hs(s){
    //计算分钟
    //算法：将秒数除以60，然后下舍入，既得到分钟数
    var h;
    h  =   Math.floor(s/60);
    //计算秒
    //算法：取得秒%60的余数，既得到秒数
    s  =   s%60;
    //将变量转换为字符串
    h    +=    '';
    s    +=    '';
    //如果只有一位数，前面增加一个0
    h  =   (h.length==1)?'0'+h:h;
    s  =   (s.length==1)?'0'+s:s;
    console.log(h+':'+s);
    return h+':'+s;
  }