1. const btn = document.getElementById('btn1')
    2. btn.addEventListener('click', event => {
    3.     console.log('clicked')
    4. })
    1. <button id = "btn1"></button>
    3. // 通用事件绑定函数 elem: 元素  type: click这种类型  fn事件监听的回调函数
    4. function bindEvent(elem, type, fn) {
    5.   elem.addEventListener(type, fn)
    6. }
    8. const btn1 = document.getElementById('btn1')
    9. bindEvent(btn1, 'click', event => {
    10.   console.log(event.target)  // 获取触发点击的元素
    11.   event.preventDefault()     // 阻止默认行为
    12.     alert('clicked')
    13. })