使用正确的图像更新模态

Question

我想要实现的是modal_img在modal打开时显示。但我似乎无法弄清楚如何去做。

<img class="modal_click" src="images/4.jpg">
      <div class="modal" onclick="modal_click;">
        <div class="modal-content">
          <span class="close">X</span>
            <img class="modal_img" src="images/4.jpg">
          </div>
      </div>
    <img class="modal_click" src="images/gandhi.jpg">
      <div class="modal" onclick="modal_click;">
        <div class="modal-content">
          <span class="close">X</span>
            <img class="modal_img" src="images/gandhi.jpg">
          </div>
      </div>

此时，一旦我遍历所有图像，我想更新DOM以包含正确的图像。

for(var i = 0; i < modal_click.length; i++)
  {  
      modal_click[i].onclick = function()
      {
          modal.style.display = "block";
      }
    }
}
span.onclick = function() {
    modal.style.display = "none";
}
window.onclick = function(event) {
    if (event.target == modal) {
        modal.style.display = "none";
    }
}