DOM

<!DOCTYPE html>
<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title></title>
</head>
<body>
    <p id="div">Hello</p>
    <button id="btn" text="" runat="server">按钮</button>
    <script type="text/javascript">

        //document.getElementById("div").innerHTML = "world";

        //方法一：直接添加
        document.getElementById("btn").addEventListener("click", function () {
            alert(1);
        });

        //方法二：多个句柄
        var x = document.getElementById("btn");

        x.addEventListener("click", hello);
        x.addEventListener("click", world);
        //移除hello事件
        x.removeEventListener("click", hello);

        function hello() {
            alert("Hello");
        }
        function world() {
            alert("world");
        }
    </script>
</body>
</html>