Javascript中添加事件到脚本被覆盖-木庄网络博客

本文摘自PHP中文网，作者逆旅行人，侵删。

问题：添加到脚本中被覆盖？

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>php.cn</title>
</head>
<body>
    <button onclick="">按钮2</button>
    <script>
           const btn2=document.querySelector("button");
           btn2.onclick=function(){
               alert("你好");
           }
           btn2.onclick=function(){  //这个会覆盖上面的onclick
               alert("我也很好");
           }
    </script>
</body>
</html>

解决方法：

1. 将二者合并在一起

<script>
          const btn2=document.querySelector("button");
          btn2.onclick=function(){
              alert("你好");
               alert("我也很好");
          }
   </script>

2.添加事件监听器

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>php.cn</title>
</head>
<body>
    <button>按钮2</button>
    <script>     
         const btn1=document.querySelector("button");
           console.log(btn1);
           btn1.addEventListener("click",()=>alert("你好"));
           btn1.addEventListener("click",function(){
               alert("我也很好")
           });
    </script>
</body>
</html>