SOURCE

setTimeout(function () {
  var btn = document.getElementById('btn');

  console.log('btn', btn);
  console.log('input', document.querySelector('textarea'));

  btn.addEventListener('tap', function () {
    console.log('tap');
    var popup = document.getElementById('popup');
    popup.setAttribute('class', 'display-none');
  })


}, 500)

<div>
  <div class="tip">
    <h2>zepto 穿透示例</h2>
    <h4>请在移动设备上查看</h2>
  </div>
  <textarea placeholder="这是一个输入框"></textarea>
  <div class="popup" id="popup">
    <span>这是一个弹出窗口哦 ~_~</span>
    <div id="btn">关闭弹出窗口</div>
  </div>
</div>

.tip {
  position: absolute;
  top: 0;
  left: 0;
  text-align: center;
  width: 100%;
}
textarea {
  width: 65%;
  height: 100px;
  margin-left: 17.5%;
  margin-top: 200px;
  border: 1px solid green;
  border-radius: 4px;
}
.popup {
  position: fixed;
  top: 0;
  left: 0;
  height: 100%;
  width: 100%;
  background-color: rgba(0,0,0,.5);
  text-align: center;
}
.popup span{
  display: block;
  margin-top: 150px;
  color: white;
}
.popup div {
  width: 130px;
  height: 50px;
  line-height: 50px;
  border-radius: 8px;
  outline: none;
  border: 0px;
  background-color: white;
  margin: auto;
  margin-top: 50px;
}
.display-none {
  display: none;
}