Javascript modal 需要点击两次才能打开

Question

代码应在单击按钮后打开模式窗口，但第一次打开它时，需要单击两次按钮才能打开它。 在从 W3Schools 复制一些代码并修改它以使其适合我的 JS 文件后，我遇到了这个问题。

HTML

<h2>Modal Example</h2>

<!-- Trigger/Open The Modal -->
<button id="myBtn" onclick="modalFunction()">Open Modal</button>

<!-- The Modal -->
<div id="myModal" class="modal">

  <!-- Modal content -->
  <div class="modal-content">
    <span class="close">×</span>
    <p>Some text in the Modal..</p>
  </div>

</div>

Java 脚本

function modalFunction() {
// Get the modal
var modal = document.getElementById('myModal');

// Get the button that opens the modal
var btn = document.getElementById("myBtn");

// Get the <span> element that closes the modal
var span = document.getElementsByClassName("close")[0];

// When the user clicks the button, open the modal 
btn.onclick = function() {
    modal.style.display = "block";
}

// When the user clicks on <span> (x), close the modal
span.onclick = function() {
    modal.style.display = "none";
}

// When the user clicks anywhere outside of the modal, close it
window.onclick = function(event) {
    if (event.target == modal) {
        modal.style.display = "none";
    }
}
}

Answer 1

如果您将事件加载处理程序移到函数之外，它将按预期工作。

这里我只是删除了函数和内联脚本处理程序。

我还将 onlick 更改为较新的 addEventListener，这里有一个很好的答案来解释它们的区别:addEventListener vs onclick

请注意，脚本需要在页面加载时运行，而不是之前

// Make sure DOM is loaded before access any of its elements
window.addEventListener('load', function() {

  // Get the modal
  var mdl = document.getElementById('myModal');

  // Get the button that opens the modal
  var btn = document.getElementById("myBtn");

  // Get the <span> element that closes the modal
  var spn = document.getElementsByClassName("close")[0];

  // When the user clicks the button, open the modal 
  btn.addEventListener('click', function(ev) {
    mdl.style.display = "block";
    // Prevent event bubbling (so in this case the window listener
    // won't catch the event and simply close it immediately)
    ev.stopPropagation();
  });

  // When the user clicks on <span> (x), close the modal
  spn.addEventListener('click', function() {
    mdl.style.display = "none";
  });

  // When the user clicks anywhere outside of the modal, close it
  window.addEventListener('click', function(ev) {
    if (!mdl.contains(ev.target)) {
      mdl.style.display = "none";
    }
  });
});

.modal {
  position: relative;
  display: none;
  border: 1px solid black;
}
.close {
  position: absolute;
  display: block;
  color: white;
  background: red;
  padding: 3px 5px;
  right: 0;
  top: 0;
}

<h2>Modal Example</h2>

<!-- Trigger/Open The Modal -->
<button id="myBtn">Open Modal</button>

<!-- The Modal -->
<div id="myModal" class="modal">

  <!-- Modal content -->
  <div class="modal-content">
    <span class="close"> X </span>
    <p>Some text in the Modal..</p>
  </div>

</div>