在不同的div上一次折叠一个

<div class="accordion">
  <div class="item">
    <div class="title">标题1</div>
    <div class="content">内容1</div>
  </div>
  <div class="item">
    <div class="title">标题2</div>
    <div class="content">内容2</div>
  </div>
  <div class="item">
    <div class="title">标题3</div>
    <div class="content">内容3</div>
  </div>
</div>

.accordion .item {
  border: 1px solid #ccc;
  margin-bottom: 10px;
}

.accordion .title {
  background-color: #f0f0f0;
  padding: 10px;
  cursor: pointer;
}

.accordion .content {
  display: none;
  padding: 10px;
}

var items = document.getElementsByClassName('item');

for (var i = 0; i < items.length; i++) {
  items[i].addEventListener('click', function() {
    var content = this.getElementsByClassName('content')[0];
    if (content.style.display === 'none') {
      content.style.display = 'block';
    } else {
      content.style.display = 'none';
    }
  });
}