单击图像时我无法放大图像，为什么

Question

我正在使用JavaScript单击图像放大。该程序可以使我开始更改和保存代码，但不幸的是没有保留备份副本。对于我想要的，当我单击图像时，我希望它以较大的形式显示图像，但是图像没有显示并且“ x”没有关闭图像，我也想单击侧面屏幕上的图像以关闭图像，但这并不像按下“ x”按钮时显示和关闭图像一样重要

 function openModal(id) {
   // 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(id);
    var modalImg = document.getElementById("img01");
    var captionText = document.getElementById("caption");

      modal.style.display = "block";
      modalImg.src = img.src;
      captionText.innerHTML = img.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";
    }

} 

.render_center{
    margin-right: .5%;
}
.img id="myImg"


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

<img id="myImg1" style = "width: 480px; height: 384px;" class = "render_center" src="https://www.gstatic.com/webp/gallery/1.sm.jpg" alt="" onclick="openModal(this.id)">

			<img id="myImg2" style = "width: 480px; height: 384px;" class = "render_center" src="https://www.gstatic.com/webp/gallery/2.jpg"alt="" onclick="openModal(this.id)">