从event.target获取子元素

// HTML
<ul id="parent">
  <li>子元素1</li>
  <li>子元素2</li>
  <li>子元素3</li>
</ul>

// JavaScript
const parent = document.getElementById('parent');
parent.addEventListener('click', function(event) {
  if (event.target.tagName === 'LI') {
    console.log('点击了子元素：', event.target.textContent);
  }
});

// HTML
<div id="parent">
  <button>按钮1</button>
  <button>按钮2</button>
  <button>按钮3</button>
</div>

// CSS
.selected {
  background-color: yellow;
}

// JavaScript
const parent = document.getElementById('parent');
parent.addEventListener('click', function(event) {
  if (event.target.tagName === 'BUTTON') {
    event.target.classList.toggle('selected');
  }
});