<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>事件</title>
</head>
<body>
<button id="btn1" onclick="fun1('1')" >按钮1</button>
<button id="btn2" >按钮2</button>
<script>
function fun1(a){
alert("fun1执行"+a)
}
//方式2 动态
let btn2 = document.getElementById("btn2");
btn2.onclick = function (){
//执行
alert("fun2执行");
};
</script>
</body>
</html>