e.target与e.currentTarget的区分

    <div id="a">
      <div id="b">
        <div id="c">
          <div id="d">哈哈哈哈哈</div>
        </div>
      </div>
    </div>

const a = document.getElementById('a')
const b = document.getElementById('b')
const c = document.getElementById('c')
const d = document.getElementById('d')
a.addEventListener('click', (e) => {
  const {
    target,
    currentTarget
  } = e
  console.log(`target是${target.id}`)
  console.log(`currentTarget是${currentTarget.id}`)
})
b.addEventListener('click', (e) => {
  const {
    target,
    currentTarget
  } = e
  console.log(`target是${target.id}`)
  console.log(`currentTarget是${currentTarget.id}`)
})
c.addEventListener('click', (e) => {
  const {
    target,
    currentTarget
  } = e
  console.log(`target是${target.id}`)
  console.log(`currentTarget是${currentTarget.id}`)
})
d.addEventListener('click', (e) => {
  const {
    target,
    currentTarget
  } = e
  console.log(`target是${target.id}`)
  console.log(`currentTarget是${currentTarget.id}`)
})

打印出：

target是d currentTarget是d
target是d currentTarget是c
target是d currentTarget是b
target是d currentTarget是a

总结：
e.target：触发事件的元素
e.currentTarget：绑定事件的元素