弹出信息窗口js

<div id="myModal" class="modal">
  <div class="modal-content">
    <span class="close-button">&times;</span>
    <p>这是一个自定义模态框！</p>
    <button id="confirmBtn">确定</button>
  </div>
</div>
<button id="openModalBtn">打开模态框</button>

.modal {
  display: none;
  position: fixed;
  z-index: 1;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  overflow: auto;
  background-color: rgba(0,0,0,0.4);
}

.modal-content {
  background-color: #fefefe;
  margin: 15% auto;
  padding: 20px;
  border: 1px solid #888;
  width: 80%;
}

.close-button {
  color: #aaa;
  float: right;
  font-size: 28px;
  font-weight: bold;
}

.close-button:hover,
.close-button:focus {
  color: black;
  text-decoration: none;
  cursor: pointer;
}

document.getElementById('openModalBtn').addEventListener('click', function() {
  document.getElementById('myModal').style.display = 'block';
});

document.querySelector('.close-button').addEventListener('click', function() {
  document.getElementById('myModal').style.display = 'none';
});

document.getElementById('confirmBtn').addEventListener('click', function() {
  alert('你点击了确定按钮！');
  document.getElementById('myModal').style.display = 'none';
});