js之绑定事件的几种方法

1.嵌入dom

<button onclick="open()">按钮</button>

<script>
function open(){
  alert(1)
}
</script>

2.直接绑定

<button id="btn">按钮</button>
<script>
document.getElementById('btn').onclick = function(){
  alert(1)
}
</script>

3.事件监听

<button id="btn">按钮</button>
<script>
document.getElementById('btn').addEventListener('click',function(){
  alert(1)
})
//兼容IE
document.getElementById('btn').attachEvent('click',function(){
  alert(1)
})
</script>

4、事件委托