单击第二个元素时不关闭下拉列表

var dropdown = document.getElementById("dropdown");
var elements = dropdown.getElementsByTagName("li");

for (var i = 0; i < elements.length; i++) {
  elements[i].addEventListener("click", function(event) {
    event.stopPropagation(); // 阻止事件冒泡
    event.preventDefault(); // 阻止默认行为

    // 处理点击事件
    if (this === elements[1]) {
      // 第二个元素被点击时的逻辑
    }
  });
}

<div class="dropdown">
  <button class="dropdown-toggle">下拉列表</button>
  <ul class="dropdown-menu">
    <li>选项1</li>
    <li>选项2</li>
    <li>选项3</li>
  </ul>
</div>

.dropdown .dropdown-menu {
  display: none;
}

.dropdown.open .dropdown-menu {
  display: block;
}

var dropdown = document.querySelector(".dropdown");
var elements = dropdown.querySelectorAll(".dropdown-menu li");

dropdown.addEventListener("click", function(event) {
  dropdown.classList.toggle("open");
});

for (var i = 0; i < elements.length; i++) {
  elements[i].addEventListener("click", function(event) {
    if (this === elements[1]) {
      // 第二个元素被点击时的逻辑
    }
  });
}