标标哟
使用事件代理，比循环点击的效率好很多，也更规范。为li添加点击事件如下：<ul id="todo-app">
<li class="item">Walk the dog</li>
<li class="item">Pay bills</li>
<li class="item">Make dinner</li>
<li class="item">Code for one hour</li>
</ul>第一种 使用循环：document.addEventListener('DOMContentLoaded', function() {
let app = document.getElementById('todo-app');
let items = app.getElementsByClassName('item');
// 给每个列表项添加事件监听器
for (let item of items) {
item.addEventListener('click', function() {
alert('you clicked on item: ' + item.innerHTML);
});
}
});第二种 事件代理：document.addEventListener('DOMContentLoaded', function() {
let app = document.getElementById('todo-app');
// 给容器添加事件监听器
app.addEventListener('click', function(e) {
if (e.target && e.target.nodeName === 'LI') {
let item = e.target;
alert('you clicked on item: ' + item.innerHTML);
}
});
});