如何使用JavaScript放大图像？

Question

我想单击此图像并使它变大：

单击图像后应该是这样的：

我将JavaScript代码放在另一个文件中以进行排序，但现在它没有响应。 它基本上没有任何作用。我想要的是单击图像，然后以各种模型显示图像。 一旦弄清楚如何将添加图像。 每一项都在同一文件夹中的不同文件中。

这是HTML代码

<script type="text/javascript" src="JavaScript_formatting.js"></script> 
<link href="stylesheet.css" rel="stylesheet" type="text/css" />

<img id="myImg" style = "width: 480px; height: 384px;" src="7.jpg" alt="Image_wallpaper">
       <div id="myModal" class="modal">
            <span class="close">×</span>
    <img class="modal-content" id="img01">
        <div id="caption"></div>
    </div>

这是CSS代码

img id="myImg"

#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(0.1)} 
  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;
}

这是JavaScript代码

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

// Get the image and insert it inside the modal - use its "alt" text as a 
caption
var img = document.getElementById('myImg');
var modalImg = document.getElementById("img01");
var captionText = document.getElementById("caption");
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";
}

更新：使用提供的答案，我尝试了您的建议。 但是，当我单击图片时会发生这种情况，这不是我想要的：

Answer 1

您的代码没有响应，因为您试图在页面完全加载之前运行代码，这意味着您的Javascript不了解DOM（文档对象模型）中的元素，因此将无法正常运行。 因此，仅应在使用window.onload加载页面时运行代码。

另外，您需要将图像源（使用src属性）添加到第二个图像标签：

<img src="7.jpg" class="modal-content" id="img01">

请参见下面的示例：

 window.onload = function() { // add window.onload here and set it euqal to a function // Get the modal var modal = document.getElementById('myModal'); // Get the image and insert it inside the modal - use its "alt" text as a caption var img = document.getElementById('myImg'); var modalImg = document.getElementById("img01"); var captionText = document.getElementById("caption"); 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"; } } // close the function 

 #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(0.1) } 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; } 

 <img id="myImg" style="width: 200px; height: 184px;" src="https://media.wired.com/photos/5926db217034dc5f91becd6b/master/w_1904,c_limit/so-logo-s.jpg" alt="Image_wallpaper"> <div id="myModal" class="modal"> <span class="close">×</span> <img src="https://media.wired.com/photos/5926db217034dc5f91becd6b/master/w_1904,c_limit/so-logo-s.jpg" class="modal-content" id="img01"> <div id="caption"></div> </div>