点击图片放大功能故障修复：仅首张图片可放大的解决方法

你遇到的问题根源在于HTML元素的id属性必须是唯一的——你给两张图片都用了id="myImg"，而document.getElementById("myImg")只会返回页面中第一个匹配这个id的元素，所以只有第一张图片绑定了点击事件，第二张完全没被JS选中。

我们可以通过以下几步修复：

1. 把图片的id改成类名，比如class="myImg"，这样可以批量选中所有图片
2. 修改JS代码，用document.querySelectorAll获取所有图片元素，然后给每一个都绑定点击事件
3. 保留原有的模态框逻辑，因为所有图片都共用同一个模态框展示

下面是修改后的完整代码：

<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
.myImg:hover {opacity: 0.7;}

/* The Modal (background) */
.modal {
  display: none; /* Hidden by default */
  position: fixed; /* Stay in place */
  z-index: 1; /* Sit on top */
  padding-top: 100px; /* Location of the box */
  left: 0;
  top: 0;
  width: 100%; /* Full width */
  height: 100%; /* Full height */
  overflow: auto; /* Enable scroll if needed */
  background-color: rgb(0,0,0); /* Fallback color */
  background-color: rgba(0,0,0,0.9); /* Black w/ opacity */
}

/* Modal Content (image) */
.modal-content {
  margin: auto;
  display: block;
  width: 80%;
  max-width: 700px;
}

/* Caption of Modal Image */
#caption {
  margin: auto;
  display: block;
  width: 80%;
  max-width: 700px;
  text-align: center;
  color: #ccc;
  padding: 10px 0;
  height: 150px;
}

/* Add Animation */
.modal-content, #caption {
  -webkit-animation-name: zoom;
  -webkit-animation-duration: 0.6s;
  animation-name: zoom;
  animation-duration: 0.6s;
}

@-webkit-keyframes zoom {
  from {-webkit-transform:scale(0)}
  to {-webkit-transform:scale(1)}
}

@keyframes zoom {
  from {transform:scale(0)}
  to {transform:scale(1)}
}

/* The Close Button */
.close {
  position: absolute;
  top: 15px;
  right: 35px;
  color: #f1f1f1;
  font-size: 40px;
  font-weight: bold;
  transition: 0.3s;
}

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

/* 100% Image Width on Smaller Screens */
@media only screen and (max-width: 700px){
  .modal-content {
    width: 100%;
  }
}
</style>
</head>
<body>

<img class="myImg" src="img_snow.jpg" alt="Snow" style="width:100%;max-width:300px">
<img class="myImg" src="img_snow.jpg" alt="Snow" style="width:100%;max-width:300px">

<!-- The Modal -->
<div id="myModal" class="modal">
  <span class="close">&times;</span>
  <img class="modal-content" id="img01">
  <div id="caption"></div>
</div>

<script>
// Get the modal
var modal = document.getElementById("myModal");

// Get all images and insert the clicked one inside the modal
var imgs = document.querySelectorAll(".myImg");
var modalImg = document.getElementById("img01");
var captionText = document.getElementById("caption");

// Loop through all images to bind click events
imgs.forEach(function(img) {
  img.onclick = function(){
    modal.style.display = "block";
    modalImg.src = this.src;
    captionText.innerHTML = this.alt;
  }
});

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

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

// Optional: Close modal when clicking outside the image
window.onclick = function(event) {
  if (event.target == modal) {
    modal.style.display = "none";
  }
}
</script>

</body>
</html>

• 将图片的id="myImg"改为class="myImg"，符合HTML规范（id唯一，class用于批量元素）
• 用document.querySelectorAll(".myImg")获取所有图片，然后通过forEach循环给每个图片绑定点击事件
• 新增了点击模态框背景关闭弹窗的可选逻辑，提升用户体验（如果不需要可以删掉这部分）

内容的提问来源于stack exchange，提问作者Adrian