扣奖（定时器）

<input type = "number"id = "qaz"value = "" >
    <button onclick = "fu()"id = "yhn" > 提交 < /button> 
<input type = "text"value = "0"id = "rfv"style = "display: none;"readonly ="readonly" >
    <button id = "edc"style = "display: none;" > 抽奖 < /button>

let qaz = document.getElementById("qaz");
    let edc = document.getElementById("edc");
    let rfv = document.getElementById("rfv");
    let yhn = document.getElementById("yhn");
    edc.onclick = function() {
      rfv.value++;
    }
    function fu() {
      if (qaz.value <= 17) {
        alert('未成年');
      } else if (qaz.value >= 18 && qaz.value < 40) {
        alert('青少年');
      } else if (qaz.value >= 40 && qaz.value < 60) {
        alert('中年');
      } else if (qaz.value >= 60 && qaz.value <= 100) {
        alert('低保户');
        edc.style.display = "inline-block";
        rfv.style.display = "inline-block";
        setTimeout(function() {
          if (rfv.value > 20 && rfv.value < 30) {
            alert('抽奖成功');
            edc.style.display = "none";
            rfv.style.display = "none";
            qaz.style.display = "none";
            yhn.style.display = "none";
          } else if (rfv.value >= 30 && rfv.value < 40) {
            alert('B');
            edc.style.display = "none";
            rfv.style.display = "none";
            qaz.style.display = "none";
            yhn.style.display = "none";
          } else if (rfv.value >= 40 && rfv.value <= 50) {
            alert('A');
            edc.style.display = "none";
            rfv.style.display = "none";
            qaz.style.display = "none";
            yhn.style.display = "none";
          } else if (rfv.value > 50) {
            alert('SSS');
            edc.style.display = "none";
            rfv.style.display = "none";
            qaz.style.display = "none";
            yhn.style.display = "none";
          } else {
            alert('失败');
            edc.style.display = "none";
            rfv.style.display = "none";
            qaz.style.display = "none";
            yhn.style.display = "none";
          }
        }, 5000)
      }
    }