js打开模式对话框

<div id="modal" class="modal">
  <div class="modal-content">
    <span class="close-button">&times;</span>
    <p>这是一个模式对话框</p>
    <button id="close-modal">确定</button>
  </div>
</div>

.modal {
  display: none; /* 默认隐藏 */
  position: fixed;
  z-index: 1;
  left: 0;
  top: 0;
  width: 100%;
  height: 100%;
  overflow: auto;
  background-color: rgba(0,0,0,0.4); /* 半透明背景 */
}

.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.addEventListener('DOMContentLoaded', function() {
  var modal = document.getElementById('modal');
  var btn = document.createElement('button'); // 假设有一个按钮来打开对话框
  btn.innerHTML = '打开模式对话框';
  btn.onclick = function() {
    modal.style.display = 'block';
  };
  document.body.appendChild(btn);

  var span = document.getElementsByClassName('close-button')[0];
  var closeBtn = document.getElementById('close-modal');
  span.onclick = function() {
    modal.style.display = 'none';
  };
  closeBtn.onclick = function() {
    modal.style.display = 'none';
  };
  window.onclick = function(event) {
    if (event.target == modal) {
      modal.style.display = 'none';
    }
  };
});